Flowering and Fruiting - Northern Research Station

- - - - - - -

7

Northeastern Forest Experiment Station d'

Upper Darby, Pennsylvania Ralph W. Marquis, Director

i a

Sta lion paper no. 60

O t

I. $onatCam ZL! W&& f 953

4

.. I

/

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United States Department of Agriculture 0 Forest Service

1 - A

Notes on

Flowering

and

Fruiting of Northeastern

Trees 1

* - L-.

N T E N T S

Page

INTRODUCTION . . . . . . . . . . . . . . . . . ?LE (ACER) Floweringhabits . . . . . . . . . . . . . . 3 . . . . . . . . . . . . . . . Effect of age 5 Flowering and f r u i t i n g pa t te rn . . . . . . 5 Phenology . . . . . . . . . . . . . . . . . 7

ASH (FRAXINUS) General . . . . . . . . . . . . . . . . . . 10 ?henology . . . . . . . . . . . . . . . . . 10 Flowering and f r u i t i n g pa t te rn . . . . . * . a 13

UAI

FII

SPRUCE (PICW) Flowering habits . . . . . . . . . . . 18 Phenology . . . . . . . . . . . . . . . . . 21 Fruit ing pa t te rn . . . . . . . .

PTNE (PINUS) . . . . . . . . . . . Flowering habits 22 5ffect of age . . . . . . . . . . . . 23 . . . . . . . . . . . , . . . . . 'henology 24 . . . . . . Flowering and f r u i t i n g pat terns 25 . . . . . . . . . . . ? rac t i ca l application 27

. . . . . . . . . . . . . GENERAL CONCLUSIONS 31

UNFRUITFULNESS: CONSEQUENCES AND REMEDIES . 33 Effects on research . . . . . . . . . . . . 33 Lessening the e f f ec t s . . . . . . . . . . . 35

Notes on

Flowering and Fruiting of Northeastern Trees

J o n a t h a n W . Wright, g e n e t i c i s t 1 . .

N o r t h e a s t e r n F o r e s t E x p e r i m e n t S t a t i o n F o r e s t S e r v i c e , U. S . D e p t . A g r i c u l t u r e

I N T R O D U C T I O N

Most published observations on the flowering and f r u i t i n g habi ts of f o r e s t t r e e s have dea l t with the period- i c i t y of f r u i t i n g i n en t i r e species. This i s natural s ince the main reason fo r making such observations has been the forecasting of seed crops.

I n tree-breeding research, however, , individual t r e e s a re important. The t r e e breeder would l i k e t o know--

On what date w i l l a t r e e flower?

e How much v a r i a b i l i t y i s there within and be6ween species i n flowering and f r u i t i n g habits?

' s tat ioned a t the bhrris Arboretum, Philadelphia, i n cooperation with the Univers i ty o f Pennsylvania.

I 7

0 I s s i z e of flower crop a good ind ica tor of s i z e of f r u i t crop? I f not, a r e there obvious reasons f o r t h e dis- crepancy?

, Is per iod ic i ty of male and female flower crops the same?

What e f f ec t does age have on flowering?

Can flowering and f r u i t i n g habi ts be e a s i l y modified by chemical o r physical st imulation or by climate?

Observations made i n connection with tree-breeding a c t i v i t i e s of the Northeastern Forest Fjrperiment S t a t i on i n 1947-51 supply some answers t o t h e f i r s t th ree questions. But only l imi ted information has been obtained on t h e other three .

For f i r s t dates of flowering of a wide var ie ty of t r e e s and shrubs i n t h e Philadelphia area, see Meehan (10).

Most of the t r e e s studied a r e located i n t he Morris Arboretum of t he University of Pennsylvania, a t Philadel- phia, Pa.; on t he campus of Haverford College, Haverford, Pa.; a t Westtown School, Westtown, Pa.; and i n Andorra Nur- se r ies , Conshohocken, Pa. Most of t he specimens were planted. Their or igins were unknown. A l l specimens were nearly o r completely open-grown.

For some species (red, Norway, and sugar maples; eas tern white, Austrian, and Scotch pines; and white and green ash) conclusions a s t o t he proportion of t r e e s t h a t a r e f r u i t f u l were strengthened by casual observations of several hundred specimens i n addi t ion t o those on which records were kept.

The phenological observations were made each year on t he same general population of t r e e s , but were of ten made-- especia l ly i n the unf ru i t fu l groups--on d i f f e r en t individuals. The extent of individual var ia t ion and constancy i s de$&@bed under t h e various genera.

For purposes-of record, f r u i t crops were c l a s s i f i e d as&Yery lJ+a%y,:' -heavy, medium, l i g h t , very l i gh t , o r none. The respective numerical ra t ings used were 5, 4, 3 , 2, 1, and 0. C

I

h d e r l i n e d numbers in parentheses refer to Literature Cited, page 37.

I

2

Che s i ze of a flower o r f r u i t crop mas Ly e s t i m -om the ground i n terms t h a t could be t Led i n t number per branch oP t r e e ; and allowances were maue f o r sin

t e r m "heavy," "med ~ n d so on, a s used t lit crop, a r e r e l a t i )r example, a crop c

uu acurrls 11-urn a l a rge oak migh medium f r u i t crop t ryman who needs 100 acorns, a l i g h t crop t o a forest ieeds a bushel, and a very l i g h t crop t o i

who spent 2 weeks bagging thousands of flowe,

usual: ated f~

. The 5 a f ru --- n--

f t r e e , escribf nn ---.

nurse] r who I reeder

iquate i n thz ;ection of tlr

pec;laa :I-t: WCL-c: S C V C I - ~ ~ i l t s t & r i r ; = a i n which difference n flowc uspected t o here m i n which lack . t e of race ra tner than species.

)f t h e I

.s not

.-- --- observz a rep] -

l t ions ~ e s e n t a 1 2 , -

may bc t i v e (

.L.....-ae

be duc of flc

s t o r )we ring

or igi r attri t

were s' ~ t h e r s

3 .

F l o w e r i n g H

ice of Grant { , ion method a s an i s o l a t i n g mecha 10 percent of t h e diagnostic cha ipecies a r e found i n t he 'flower

i n p lan t s pol l inated by other i n s e c ~ s diagnostic characters a r e found pol l inated p lan t s only 4 percent.

ted out , t he i nportar n angiosperms. aome s t h a t d i f f e r en t i a t e ee-pollinated plants .

'' ~ e r c e n t of t h e 1-

9 1 3 P he f lc

The mar They -.-- -.

~ l e s provide a good r a t i on of t h i s ten( a r e primarily bee- ated, and near ly a:

;pecfes are well d i f fe ren t ia ted i-_ _ . a1 characters a s we: a s i n fol iage and growth ~ c t e r s . This dive ~f f l o r a l characteqs i s evidc )t only i n t h e s t ruc 3 f t h e flower and inflorescei )ut a l so i n differences i n

r s i t y t u r e (

- - - - .

;ime of Lioecio

f lowt usness ,

sring t knde 1 dicho

I n mosl . HOP unc t i 0 1

i e s t k specie . If . .

le f l ~ w ~ ~ - ~ -re s t ruc tura l . as observed t he flow ? the p i s t i l was fu

though they rmgnr; I

Conversely, t he p i 11 and nonfunction,

.e spar;. i n t h e lerfect

rers we: mc tioni 2 - 2 - 1

)erfect lever f ;he anthers Sailed

a s l a rge a s f e i t h e r lacki

L~l LIPS male flowers.

tlisce, nal ant was VE

even ;hers. t r y sma

Section Platanoi'dea i s the most primitive (Q. Acer platanoides i s typical . I t s flowers have calyx, corol la , stamens, and p i s t i l . I n female flowers t he anthers become nearly full-sized, although they a r e nonfunctional; and the p i s t i l i s 5-6 mm. long. I n male flowers the p i s t i l i s only 1-2 mrn. long. The t r e e s a r e monoecious, There i s nearly complete dichogamy (&), with l i t t l e overlapping of male and female flowering periods. Each flowering period lasts 2-4 days, and the t r e e flowers over a period of 1-2 weeks.

Other species i n the sect ion have s imi la r flower and inflorescence s t ructures . The s ing le t r e e s avai lable of th ree other species had successive flowering periods t h a t were e n t i r e l y male. The dichogamy pa t te rn found i n A. p l a t - anoides was a l so t yp i ca l of A. buergerianum (section ~ p i c a t a ) and of A. palmatum and A . .japonicum (sect ion ~ a l m a t a ) .

Even i n a dichogamous species l i k e A . platanoides there i s a s l i g h t tendency toward dioeciousness: 3 of 32 t r e e s observed produced nothing but male flowers i n each of 5 years.

I n A. saccharum (sect ion ~ a c c h a r i n a ) flower reduction has progressed fa r ther : t h e corol la has been l o s t . Dicho- gamy i s very incomplete and na tura l s e l f i ng i s probable on most t rees . A t l e a s t i n t he Philadelphia area there i s a pronounced tendency toward dioeciousness, f o r most of t he t r e e s the re produce only male flowers o r male flowers with a few female flowers.

I n A . rubrum and A . saccharinum (sect ion ~ u b r a ) the re i s a tendency toward dioeciousness r a the r than toward dichogamy. The majority of t r e e s observed a r e purely male o r female--although some had both types of flowers. The flow-= e r s remain s t ruc tu r a l l y perfect , although A . saccharinum has l o s t i t s corol la . The inflorescence has been reduced much, t o four o r f i ve flowers. I n these species a l l flowers on a t r e e a r e within a day o r so of each other in ' s tage of devel-- opment, and t h e probable receptive period f o r individual t r e e s l a s t s from a few days t o a week.

Reduction of flower pa r t s i s a l s o strongly pronounced i n A , ne~tundo ( sec t ion ~egundo) . There i s complete dioeciousness, the coro l la i s lacking, t h e calyx i s very small, and male and female flowers contain no rudimentary pa r t s of the opposite sex. A l l flowers on a t r e e a r e a t nearly t he

3~ome.nclature i n this report follows Rehder (14).

same s tage of development a t any one time. Pollen-shedding l a s t s about 4-8 days f o r individual t rees , and t h e period of recep t iv i ty l a s t s about twice as long on female t r ee s . I n A . henryi t he flowers a r e s imi la r ly reduced, and pollen- shedding l a s t s a week o r more on individual t rees .

I n A . saccharum there was a noticeable loca l iza t ion of t h e female on ce r t a in port ions of t he t r e e crown, other branches being wholly male. I n monoecious t r e e s of A . rubrum and A. saccharinum there was a l so a tendency f o r the male and female flowers t o be local ized on ce r t a in branches, although an intimate mixture of t h e two kinds i s found sometimes on A . rubrum. I n o ther species flowering was s imi la r over the e n t i r e crown.

E f f e c t O f A g e

Most of t h e male specimens observed were 1 foo t o r more i n diameter, and p&sumably well pa s t the minimum s i z e f o r flowering. Data on t h i s point a r e avai lable only f o r A . rubrurn, some of which flowered t he fourth year from seed.

F l o w e r i n g A n d F r u i t i n g P a t t e r n

The maples observed matured a' l a rge percentage of t h e i r female flowers i n t o f r u i t every year. This w a s t r ue even of some i so l a t ed t r e e s (probably -parthenocarpic) t h a t were not cross-pollinated.

The exceptions were A . saccharinurn, which usually flowers very ear ly , so t ha t many o r a l l of t h e flowers a r e damaged by f r o s t ; A . platanoides, of which ce r t a in t r e e s f a i l e d t o mature f r u i t i n 1948; and A . rubrum, of which one specimenhas f a i l ed t o mature f r u i t i n 5 years, although it flowered heavily and was adequately poll inated.

As a whole t he maples flower very heavily, and the r a t i o of nonflowering t o flowering t r e e s i s small. With most species t h e amount and kind of flowers (male, female, o r both) remained f a i r l y constant from year t o year on individual trees--and of ten on port ions of individual t rees . So not only t he amount of flowering but a l so the amount of f r u i t i n g per t r e e was about t h e same from year t o year.

A. s a c c h a m i s not constant i n producing female flow- e r s . Trno of 47 t r ee s observed produced female flowers 3 years out of 4; half t h e t r e e s produced no female flowers; and t he r e s t produced female flowers only i n 19.50 o r i n 1950 and one other year. Data on constancy of male f l o w e r ~ s e t a r e lacking, but it i s known t h a t a t l e a s t three t r e e s pro-

P DENSIFL ORA (1-81

F i g u r e 1 . - - D u r a t i o n o f f e m a l e r e c e p t i v i t y o r p o l l e n - s h e d d i n g o f t r e e s i n t h e P h i l a d e l p h i a a r e a . Numbers i n p a r e n t h e s e s i n d i c a t e number o f t r e e s t h e r e c o r d s a r e b a s e d on .

duced male flowers every year. Judging from t h e d i f f i c u l t y i n f inding female flowers su i tab le f o r bagging and observa- t ion, t he r a t i o of male t o female flowers apparently i s not l e s s than 10 t o 1, and it is probably c lo se r t o 50 t o 1,

A. platanoides was l e s s variable. Nearly a l l t r e e s flowered every year, and t h e s i z e of t h e flower crops var ied by 50 t o 75 percent. Observation of 32 t r e e s f o r 5 years indicates t h a t t h e r a t i o of male t o female flowering periods i s about 2 t o 1: there were 243 male periods and 127 female periods i n t h a t time.

There a r e some data f o r a few other species. Two specimens of A . henryi flowered heavily male i n a l l years. Two specimens of A. buergerianum flowered heavily every year, both male and female. And one specimen each of A . may- rii and A. cappadocicum flowered heavily male every year. -

P h e n o l o g y

The maple species maintained the same sequence of flowering each year ( f ig . 1 ) . But t he degree t o which flower ing times of c losely re la ted species overlapped varied. I

I n 1950--but not i n other years--A. saccharinum and A. rubrum overlapped s l i gh t l y , making na tura l crossing - A. magrii and A . cappadocicum could have crossed'with A_. platanoides i n 1947 and 1950, but not i n 1949 o r 1951.

I n ' A . saccharinum, l i t t l e var ia t ion was 'found i n flowering time within a group of nat ive t r ee s ; but some planted specimens a mile away flowered 10-15 days earlie:. I n A . rubrum there was usually 2-4 days1 di f ference i n flow- e r ing time among d i f f e r en t t r e e s ; and l i t t l e constancy i n ea r l iness o r la teness of flowering was found i n individual t r e e s . I n A. negundo there was 3-21 daysf d i f ference among f i ve female t r ee s , and 2-3 daysf difference among four males, The late-flowering females were consis tent ly l a t e ,

I n A. platanoides, 34 t r e e s were observed f o r t he en- t i r e 5 years; 32 of these were i n a s ingle row along a road and t he other 2 were about hal f a mile away. These two sep- a r a t e t r e e s always flowered e a r l i e r (as much a s 2 days) than the t r e e s i n the row.

: I n t he row, individual t r e e s d i f fe red by 4r9 days i n f i r s t flowering time. The behavior of these t r e e s can be summed up t h i s way:

MAPLE IACER)

SUMMARY. ALL TREES

F i g u r e 2 . - - F r u i t i n g r e c o r d s o f i n d i v i d u a l maple t r e e s . The h e i g h t o f t h e b a r s i n d i c a t e s s i z e o f c rop , from 0 (no crop) t o 5 ( v e r y heavy c r o p ) . Each bar rep - r e s e n t s one year , from ( l e f t t o r i g h t ) 1947 t o 1 9 5 1 . Numbers i n d i c a t e groups o f two or more t r e e s .

lumber ' t r e e s

I

Flowered-

4 --car-M every year. --late every year. --early 4 years, intermediate 1 , --l.t.p 4 years, intermediate 1 y

e 4 years, e a r l y 1 # t e 2 or 3 years and

ate the r e s t of t h e time.

year. ear. --- -

year.

i f f eren

* . . timer

O A I Thus about a t h i r d or theSu -, platanc CI

~ r e e s were nu ; i n f14

'he sam

owerirq

e row

: time.

of t r e

-

e s was ? of m a !s. were

l e and female observed:

! flowe:

lale

r ing s t ~ ~ p a . equerlc t equenc e

male-f em lale lale-ma:

ue-male-f ma: a le - f ernale .e-male 'emale-male

Of t he : 32 t r e e

d t he : d t h e : d the :

same se 3ame se same se

!quence a l l 5 years. !quence 4 out of 5 y bquence 3 out of 5 y

'ears. r.

d t he : d a di:

same se Pf erent

!quenc e , seque:

2 out nce evc

of 5 y ?ry yea

hus f o r t he species hat any t r e e f male and f e

a s a m n a t ra Lowerir

rhole lndom . ~g s t a g

the chances a- .) out 01 >A" Cr . same :

.ear. chose]

male f : will k e s the

rve the next y

of cor r iod c

?robably recorded w a s a l -

' a r t of t h e apparent lack lstancy i r t i f a c t : a small male pe )f flow

ne year might h9-r- been missed t he next year. e n t i r e expe c t c

8 I I C A I U I

des t rl her ; st

o due uring 1 - ----

t o t he ;he w i n

of an !s t h e

period ?d e a r l

A S H

( F r a x i n u s )

G e n e r a l

Except f o r Fraxinus velut ina , most of the observed t r e e s were more than 8 inches i n diameter. The diameters of the smallest t r e e s observed t o flower were:

F. bungeana--2 inches F. velut ina , F. nigra, F. ornus--3 inches F. americana, F, pennsylvanica--4 inches F. excelsior--5 inches

Species of the subsection Melioides (F. americana, F. pennsylvanica, F. velutina) a r e dioecious, with extremely reducedflowers. Since ash t r e e s a rewind-po l l ina ted , the flowers of c losely re la ted species a r e s imilar .

The flowers of F, excels ior (subsection ~umel ioides) a re s t ruc tu r a l l y per fec t , having anthers and p i s t i l s . I n t h i s species t he occurrence of male, female, hermaphroditic, and var iable t r e e s has been reported (1). Only male and female t r e e s are found i n the Philadelphia area. The males have large anthers and small p i s t i l s t ha t normally f a i l t o develop (although one male produced a few seeds one year). The females have large p i s t i l s and smaller anthers; t h e an- the rs open and shed small amounts of normal-looking pollen, So f a r this pollen has been nearly inef fec t ive i n s e l f - o r c ross - fe r t i l i za t ion .

Small t r e e s observed flowered heavily o r not a t a l l . They flowered over t he en t i r e crown. However, two la rge t r e e s had var iable flower crops, and they were local ized on ce r t a in branches. It i s probable t h a t these t r ee s l a i d down buds over t he e n t i r e crown, but t h a t a l a rge proportion of the buds were winter-killed. This i s known t o have occurred on t h e lower pa r t s of t h e t r e e *

P h e n o l o g y

The phenology of the pr incipal ash species i s shown i n f igure ,l. A few addi t ional data show t h a t F. chinensis and F. oyycarpa flower a t about t h e same time a s F. pennsylvanica; t h a t F. nigra and F. quadrangulata flower a t about t h e same time a s F. excelsior--or 2-3 days l a t e r ; and t h a t F. ornus flowers a week o r more a f t e r F. pennsylvanica.

The receptive period (from flower-bud opening u n t i l + withering of t h e stigma) l a s t ed 7-10 days f o r individual fe-

male t r e e s and 2-3 weeks fo r a species. Differences of 3-4

10

-

A S H (FRAXINUS)

P E M Y L VANICA AMERCANA EXCELSIOR

i?,n~ ~YI, I

- - -

" , , ! n

m u an. -

a?a m "h nma

-

&. x -

. o w e r i n g and f r u i t l n g r e c o r d s or l n a l v l a u a l White b a r s i n d i c a t e f l o w e r i n g , b l a c k b a r s H e i g h t of b a r s i n d i c a t e s s i z e of c r o p .

A S H (FRAXINUS)

AMERICANA EXCELSIOR PEWSYL VdNlCA

u, , &- & -

b .A 1 k. -

;u m - 3

, , ,; ,,,., I-

& : - A -

L - 1 30 -?? , m

- - L

-

-? l-r 4 - - I 25 - ? m - I

- - SUMMARY, ALL TREES

- - -

F r u i t i n g recc t h e P h i l a d e l

i n d i v i d u a l a r e a , 1947-51.

days between individual trees were not constant from year t o year, but l a rge r differences of 1-2 weeks were. Most of these l a rge r d i f ferences were associated with loca t ion of t he t r ee s , although some were probably associated with geo- graphic o r ig in of t h e plant ing stock.


"7 flowering did not necessar i ly mean heavy f r u i t - i ng ( f i g . 3 . Of 48 t r e e s t h a t were used i n control led pol- l i na t i on experiments, 30 suffered nearly complete seed-crop fa i lu res . I n 1947 the f a i l u r e s were due t o a l a t e May f r o s t t h a t defol ia ted and def lora ted a l l ash t r e e s i n low-lying areas. I n other years, however, the re w a s no such obvious explanation f o r t h e heavy mortal i ty.

Only from F. excels ior has i t been possible t o get appreciable quan t i t i es of contro3-pollinated seed from nor- m l l y un f ru i t fu l t r e e s by v a r i a t i ~ n s in technique. I n t h i s species, bagging the flowering branches a f t e r pollinakion resul ted i n heavy f r u i t crops even though t h e r e s t of the t r e e bore no f r u i t .

Data on t he flowering habi ts of male t r e e s a re avai l - able f o r t he following t r ee s , which were. observed f o r 3 years 11948, 1949, 1951):

9 F. pennsylvanica flowered 3 out of 3 years. 1 11 2 out of 3 years. 4 F. americana 2 F. excels ior

" l o u t of 3 y e a r s . fl 3 out of 3 years.

1 II " 2 out of 3 years.

Frui t ing pat terns of individual t r e e s a r e shown i n f igure 4. Possibly 2 o r 3 of t he F. americana and 5 o r 10 of the F. pennsylvanica t r e e s classed a s nonfruit ing a r e ac tua l ly males. For both species 1947 and 1949 were the best f r u i t years; only one t r e e t h a t f ru i t ed i n other years f a i l ed t o f r u i t i n those 2 years. More than a t h i r d of t h e f r u i t i n g specimens of F. pennsglvanica f ru i t ed heavily 2 o r 3 years i n a row, indicat ing t ha t depletion of food reserves by a previous heavy crop does not determine f r u i t i n g perio- d ic i ty . Nor does s i z e of t he flower crop ( f i g . 3).

The r a t i o s of t o t a l t r e e s t o f r u i t i n g t r ee s ( a t l e a s t 2 years out of 5) a r e 4 t o 1 fo r F. pennsylvanica*and 7 t o 1 f o r F. americana. Thus, i n a tree-breeding program one should plant 4 o r 7 times a s many t r ee s a s a r e needed f o r female parents. Roguing of t he unf ru i t fu l t r e e s can take place a t diameters of about 6 and 8 inches respectively.

shou: i s h wl

Observation f o r three suc, accornpli.sh .&he roguing a1 males.

? years e s t ab l

No continuous observations were made on the floweri ' of the oaks. Controlled pol l inat ions were made i n 2 yea: --19-47 and 19.49, Of 17 t r ee s worked ( a l l bore heavy cro] of female flowers), matured appr 5 quant e i t h e r cont rol -pol l i 3r open-polli corns . observation of other subs tan t ia te yeneral sion t h a t heavy flow 3avy f r

only 4 .nated (

I oaks

eciablc nated ; s the

, i t i e s I

Casu . concll

)t i n d i ca te ht ' u i t ing

. foot : Most of the' t diameter, and open-grown, follows: Quercus alba, 3( carpa, and Q. pa lus t r i s , Q. lyra' - " 5 f e e t o r more; anc and Q. la, .50 f e e t o r more.

than 1 ~ h t s of these t r ee s were I . bicolor, Q , macrl

ore; Q. boreal is a] b r i ca r i a , Q . phello:

studiec - - . i were . . - more 1 . .

r;a, 3: velutir

Few observations were ma&= , , SO most o I tPD records a r e f o r only 4 years. For t he white oaks (Q. albi 9. bicolor, Q. l y r a t a , and Q. macrocarpa) 1947 was the be: year f o r the species as a whole and f o r most individui t r e e s , Only a few nens f ru year ( f i g . 5).

well i r i t e d

d i f f e r Lves . 3 t f o r

Frui t ing pat terns of t h e black those of the white oaks and a l so among t h e t r e e s f ru i t ed wel l i n 2 o r 3 years. 10s t he peak years did not cc -9

years e i t he r i n flowering or i n a many differences i n f r u i t i n g pa t t mong individuals, some of which I r u L e a Desi

f season.

oaks themsel

Excel white . Th ig spec

oak pe: lere we: i e s a] ~. . L 7 - -.

Frui t fulness i s especial portant ," u r x u u r -

weeder who i s working with oaks rol-po: . h a t e d acorns a r e poor at best . ,ime -c oi iuming, a n d e a c h f l o w e r y i e l d s bu-ca s ~ n g ~ e s t . - . Worki~ !,000 po l l ina t ion bags per man-season (6- x 14-inch bai inclosing 8-10 inches of branch) would be a laudable accol

-11ishment. A n d w o r k o f t h i s i n t ens i t y wouldy ie ld8 ,00( '1,000, 40 acc spec ti^ )caring , medi i gh t , 'ruit c

i e ld s C

culat ic .- -1 - .

)f cont In i s t ?ed .

400-2,1 very 1

rops

10, and heavy

,om t r e ~ !ry l igl

The y i !O bags ; ted i n

J UG c ~ ~ e c t e d from working 2.000 bags n CLUD U I

f o r c t ab le

- " on eac sach of

1.

ause I.--rxpecr;ea acorn .mela 01 o a ~ sp! - -

'rom work 10 bags

I snecies annual ?

I acorn

Average crosses

ng--

4 - more :arm -

40 3r more corm

yield

570 19 320 14 410 12

2,000 55 J

50 590 210 690

alba bicolor borealis imbricar Lyrata mac rocar pa lus t r i ohellos robur velutina

technique (so f a r , bagging tecl 4uced ra ther than ir s e t ) a in i n t e r spec i f i c crc sduce t ihan-annual flowerir sase t h

Faulty . .

hnique has rc lcrease mses w Ig woul

d seed o d d rc d incrf

i s i b i l i L again

fr.- +

The unfruitfulness of t he oaks--and t he pos l e c t i on f o r f ru i t fu lness may mean se lec t io r ,necess i ta tes f fa ren t breeding procedures -I&=

1 f o r o .an tho: se usec t h e r gr snera .

F I R

( A b i e s l

F i r t r e e s be !ar fern ?er t h e

a l e f lc e n t i rc

i n the 01

topmc ne exce i e catkins ov 3 crown

this respect i s a very broad-crowned sp Lepis: it bore numerous cones a t t he ranches only 8 o r 10 f e e t from the gro

e cimen ends o: und .

.es horn r l a t e r ;

reral f . t ch i i

i r species a t r e e s not inc

.re shoi :luded :

The flc r e 1.

)we r ing dates Data f o r two .n f igu

O A K :QUERCU!

rM4RY, ALL 1

cords f :or ind i v idua 1 L oak t Figure $ . - - F r u i t i n g re<

SUMMARY. ALL TREES

t he f igure i nd i ca t e t h a t t h i s species flowers about t he same time as A, lasiocarpa. The flowering periods shown coincide approximately with the period of pollen-shedding, This i s usually o n l y h a l f as long a s t he period of apparent female recept ivi ty , because t h e female flowers appear, scales a l - ready open, a few days before t he period of pollen-shedding and c lose a few days a f t e r , Li t t le o r no dichogamy was ok served,

I n every case observed, production of female flowers was accompanied by moderate t o heavy pollen production. I n addit ion, th ree un f ru i t fu l t r e e s (one A. c i l i c i c a and two A. v e i t c h i i ) have produced pollen. There was r e l a t i ve ly l i k t l e flower morta l i ty ; t he f i r s are parthenocarpic (Q). Thus t he f r u i t i n g pa t te rn f o r a t r e e i s e s sen t i a l l y s imilar t o i t s flowering pat tern .

Fru i t ing records of individual open-grown t r e e s a r e shown i n f igure 6 , The heights of t he t r e e s studied were a s follows: A. cephalonica, 30-60 f ee t ; A " c i l i c i c a , A. las io- carpa-,and A. nordmanniam9 40-50 f e e t ; A. homolepis, A. num- id ica , 30-40 f ee t ; and 8. ve f t ch i i , 25-50 fee t . These t r e e s were 40-50 years old. Pers i s ten t cone s ta lks showed t h a t most of t he f r u i t i n g t r e e s had f ru i t ed f o r many years before observations were s ta r ted , while none of t he nonfrui ters had.

The f r u i t i n g pat terns of t h e individual t r e e s do not show the consistency of b ienn ia l . f ru2 t ing t ha t i s character- i s t i c of A . balsamea i n Canada (=).

There seems l i t t l e need t o s e l ec t f o r f ru i t fu lness i n the Philadelphia area.

S P R U C E

( P i c e a )

F l o w e r i n g Habits

Norway spruce ( ~ i c e a ab ies ) bears i t s female flowers over i t s e n t i r e crown, but they tend t o ' b e more abundant i n the top. A l l other spruce species i n the Philadelphia area bear t h e i r female flowers i n t he top one-third of the crown. I n a l l species the male flowers a r e borne over the e n t i r e crown.

The heights of t h e t r ee s studied were as follows: P. abies, P , asperata, P. maximowiczii, P , o r i en t a l i s , and

F IF

>r i n d i . v i d u a l f i r t r F i g u r e 6 . - - F r u i t i n g r w o r d s fc

=, 30 f e e t o r morc o r more; P. mariana, P. montlgena more.

glauca . . 15 fec t. p o u t a , ~z f e e t c

L L ~ L L ~ , Gone crops were obser-vcu uA 3- t o 8-foo if P. abies , P. glauca, P. po l i t a , and P. asperata . been transplanted a year o r two ea r l i e r . I n each I

- 'ruiting was not repeated; so it was presumably due r;o temporary shock stimulus. But i n g e n e r a l , t ransplant i r does not seem t o be a r e l i a b l e method of inducing flowerir i n t h i s area , and many other s imi la r ly transplanted tree

b b I G C

t ha t h~ case t l

L -

,ed ea r

; area ,

1 y-.

a l l sol Lure a t I I . _ -,:uc;t: u-ees u i l

ent of t h e i r female flowers i n t o cone: 'lowering pat terns of individual t r e e s ' ru i t ing pat terns ( f ig . 7).

r lCC%Sb

lhus t h e f eml Lentical t o t l

S . 7 a re i d

'lower

~ I

few t r ~ . - .

SPRUC (PICEA)

r e ~ s ~swnnra ~ L ~ U C I IIXMWCZII W N ?

d A : J a g J : J * : A m d J A U i i - - - ;L _ L i z _ I U I 7 ' a -- ;RI *

a !i i4 ;.a

:* r 3. 3 -

I 70 . , m

-mmn". , ".. ,"cc

111 A" A ;Iru;J, J d

Figure 7 . - - F r u i t i n g recc v idual

Fxcept f o r a P. or ienta l ic 2. maximowiczii, ana r. glauca, pollen was Dorne only I t h e f r u i t i n g t r ee s . Years of female flowering did not coi respond c losely t o years of male flowering f o r individu: t rees . On the whole there were about twice as many fern:

crops a s male

So f a r , avai lable speclmer-- -- _ - _ _ poli t : and P. pungens have produced no pollen. Pollen crops c P : glauca, P. omorika, and P . or i en t a l i s have been so ligk t h a t it has been very d i f f i c u l t t o co l lec t enough f o r cor t ro l -pol l inat ion experimeni ~d very l i t t l e has sa t o open pol l inat ion, even !es growing i r s (z Only specimens of P. abie:? asperata, P_, owic z i j ~ n d P. montigena have produced moderate amounts of ;v,2n i n these species seed s e t of nonisolated t r e e s creased several times by addi t ional poll ination.

20

ees of

-

t s , an on t r e

s . P.

. mari: ma- P.

: seed 1 group #maxim

t r e e s .

The following examples provide evidence tha t flowering, or lack of it, - i s due t o genetic differences within species :

P. asperata.--Four t rees in the Morris Arbo- retum are narrow-crowned, of the same accession, and have not yet flowered. Four other t rees of a different accession are very broad-crowned, older but sharter. And each has flowered one o r more times.

P. abies.--The specimens i n the Morris Arbo- retum tha t have flowered so f a r a r e moderately broad-crowned, with pendulous branches; they a re i n two different si tuations. They a r e only half t o two-thirds a s t a l l as many other narrower- cromed specimens i n the Arboretum and v ic in i ty tha t do not flower or flower very l ight ly.

P. morika.--Each of a group of t r ees 15-20 fee t t a l l on the campus of Haverford College--all probably of the same accession--have flowered once or more. Much la rger specimens i n two other arboreta have not flowered yet.

There a re a l so evidences of climatic control over flowering. I n both 1949 and 1951 the author observed that the majority of Colorado blue spruce i n Spokane, Washington, were f ru i t ing very heavily, although they were no larger and no t h r i f t i e r than the nonfruiting specimens i n Philadelphia. The same tendency was observed i n Nomay spruce.

P h e n o l o g y

Flowering dates of spruce species a r e shown i n figure 1. Additional data indicate that : P, maximmiczii flowers even ea r l i e r than P. asperata; P. montigena flowered a day or two ea r l i e r than P. glauca i n 1951; and P. koyamai and P. o r ien ta l i s flower l a t e r than P. omorika.

By bringing male catkins in to the laboratory and l e t - t i ng them shed on paper it has been possible t o hasten pollen-shedding by only 2 or 3 days. But so f a r it has not been possible t o use as male parents species t h a t ! r more than 2 or 3 days a f t e r the species used a s fern .- ent .

-In P, abies the flowering period for individual t rees lasts 10'days'to-2 weeks. T h i s i s because there i s a luc- cession of female flowers, each of which remains receptive f o r about a week. The pollen-shedding period i s similarly extended. Differences i n flowering time between individual

t r ees a re s l ight .

I n a l l other species the female and male flowering periods each l a s t 3 or 4 days per t r ee ; they overlap by 25 t o 50 percent. A t any one time, a l l the flowers on a t r e e a re within a day of each other i n t h e i r stage of development. Individual t r ees d i f f e r from each other by a day or two.

No data were obtained on the constancy of phenolog- i c a l differences within species from year t o year.

F r u i t i n g P a t t e r n

The f ru i t ing patterns of individual open-grown trees a re ident ica l t o the patterns of female flowering. There i s i n spruce a greater tendency toward annual f ru i t ing than i n any other! group except some of the maples. Many specimens f ru i ted oeell 4 or 5 years i n a row.

1n the common species, 1950 and 1951 were the best f r u i t years, both fo r the species and f o r individual t rees . For P. glauca one reason f o r t h i s was tha t many of the t rees f ru i ted for the f i r s t time i n 1950.

I n a l l species the r a t i o of t o t a l t o f r u i t f u l t rees i s large. For P. glauca this r a t io w i l l undoubtedly be reduced as the t r ees grow older and more come in to flower. To establish a breeding arboretum fo r spruce i n this region one should plant 5-10 times as many t r ees a s a re needed f o r female parents.

F l o w e r i n g H a b i t s

I n most pine species, both male and female flowers a re borne over the en t i re crown. However, female flowers were found t o be most p len t i fu l i n the upper par t of the crown. Male flowers were l e s s plentiful--or lacking--in the few uppermost whorls.

In Pinus strobus, P. cembra, and P. koraiensis female flowers were localized i n the upper several whorls, includ- ing the leader . Nale flowers were localized i n the upper half of the crown--excluding the few uppermost whorls. The female flowers always and the male flowers generally were

borne on vigorous branches exposed t o f u l l sunlight . But i n P. strobus appreciable numbers of male flowers were found on shaded inner branches.

Male flowers always occurred on t he basal port ions of the current y e a r D s growth, female flowers a t the ap ica l por- t ions of the current yea r ' s growth. However, on a few P a thunbergii some o r a l l of t he male flowers were replaced by fenale flowers. The resu l tan t cones were normal--if not crowded, When crowded (sometimes there were 50 o r more per s h ~ o t ! , they developed t o l e s s than half normal s i z e and did not open properly.

. E f f e c t Of A g e

The minimum flowering ages of 39 pine species growing i n the Eddy Arboretum a t P lacerv i l l e , California, vary from 1 t o 13 years (2). Of 19 species grown i n both P l ace rv i l l e and Philadelphia, a l l but three s t a r t t o flower l a t e r i n Philadelphia. (P. virginiana flowers e a r l i e r , P . b a n k s i . and P. sy lve s t r i s a t about t he same time. ) The e a r l i e r flowering a t P lacerv i l l e i s not associated with greater vig- or, f o r several of the species a r e equally or more vigorous i n Philadglphia.

The approximate heights a t which pine species s t a r t t o flower i n appreciable quant i ty i n Philadelphia are as follows: P. densi f lora and P. mugo, 3 f e e t ; P. banksiana, P , pungens, P, sy lve s t r i s , and P. thunbergii, 5 f e e t ; P. ar- mndi , P, cembra, and t. parvif lora , 15 f e e t ; P. cembroides, P. nigra, P. resinosa, P. strobus, and Po taeda, 20 f ee t ; P. koraiensls , 20 f e e t o r possibly much higher; P. f l e x i l i s and P. g r i f f i t h i i , 30 fee t o r more.

There i s evidence i n th ree species t ha t minimum flowr e r ing age i s influenced by provenance. Some 30-foot P. cembra specimens probably of Central European or ig in have not - flowered; but some 12-foot specimens of probable Siberian or ig in have flowered. I n P . f l e x i l i s t he one t r e e t h a t has flowered most cons i s ten t ly and most heavily i s a runty specimen t h a t d i f f e r s from a l l o ther t r e e s of the species i n the area. A group of ra ther slow-growing s t r a i g h t Scotch pine probably of Scandinavian or ig in have not ye t flowered (20 years a f t e r outplanting) , but specimens of other or igins have.

I n t h e i r ea r ly flowering years, a l l P. strobus t r ee s observed were exclusively o r p r inc ipa l ly female, bearing up t o 400 female flowers but no o r few male flowers. Female- ness s t i l l predominates among the older t r e e s 1-2 f e e t i n

diameter , a l though most of t h e s e t r e e s do produce small t o moderate amounts of po l l en ,

I n P. d e n s i f i o r a a l s o t h e r e i s a tendency toward femaleness i n t h e f i r s t 2 o r 3 yea r s of flowering. Preco- c i t y of female f lomering was a l s o observed i n a few younger specimens of P. armandi and P. g r i f f i t h i i .

I n P. s g l v e s t r i s young t r e e s l e s s t h a n 20 f e e t t a l l were p r i n c i p a l l y e i t h e r male o r female; most a l d e r t r e e s were hermaphroditic. Schrock (2) found t h a t most of t h e 13-year-old progeny of early-blooming Scotch p ine were ex- c l u s i v e l y male o r female. However, accord ing t o Ga l spe rn (&) exc lus ive ly male o r female t r e e s a r e r a r e , a l though d i f f e r e n t p a r t s of t h e t r e e may be exc lus ive ly of one sex.

P. k o r a i e n s i s was precoc ious ly male. Of 6 t r e e s up t o 25 f e e t t a l l t h a t have flowered, on ly one has produced a s i n g l e female f lower.

Flower product ion inc reased wi th s i z e of t r e e i n n e a r l y a l l spec i e s . The i n c r e a s e was l e a s t i n P. s t robus . I n t h i s spec ies cones a r e borne only i n t h e upper crown, and t h e a r e a of t h e crown s u i t a b l e f o r cone product ion- does not i nc rease g r e a t l y wi th age. Some t r e e s produced 200 t o 300 female f lowers t h e i r f i r s t yea r , which i s n o t exceeded by most o l d e r t r e e s .

Date of f lower ing was c o r r e l a t e d w i t h taxonomic a f - f i n i t y . Spec ies of In s ignes flowered f i r s t , of Lar ic iones next , and of S t r o b i las t . There was s u f f i c i e n t overlapping between spec ies of t h e same s e r i e s t o make n e a r l y a l l i n t r a - s e r i e s c ros ses possible--except f o r P. tabulaeformis, which flowered e a r l i e r t han any o the r spec i e s i n t h e s e r i e s Lari- c iones (with most of which it does n o t c r o s s w e l l ) and was d i f f i c u l t t o match wi th males of o the r spec i e s i n t h e se- r i e s . However, t h e overlapping i n f lowering f r e q u e n t l y re- q u i r e d s e l e c t i o n f o r f lower ing t ime i n one o r both spec ies .

P h e n o l o g y

Flowering d a t e s of p ine spec i e s a r e shown i n f i g u r e 1, Addi t iona l d a t a show t h a t P. monticola (a s i n g l e specimen) f lowers about t h e same t ime a s P. s t robus ; t h a t P. k o r a i e n s i s and P. armandi f lower a few days l a t e r ; and t h a t P. cem- bro ides f lowers a week o r two l a t e r .

For i n d i v i d u a l t r e e s t h e pe r iod of pollen-shedding l a s t e d 2-5 days, and t h e per iod of female r e c e p t i v i t y (from bud opening, t o s c a l e c lo s ing ) l a s t e d up t o a week, o r

s l i g h t l y longer. A l l flowers on t he t r e e were within a day o r two of each other i n s tage of development. Sometimes there was a difference of 1 or 2 days i n t he s t a r t of female and male flowering, but there was always enough overlapping t o Amke se l f i ng probable.

Within species there was 3-5 days' difference i n onset of flowering between ea r ly and l a t e t rees . The d i f fe r - ences were nearly as g rea t within any small group a s with- i n the Philadelphia area a s a whole; and they tended t o remain constant from year t o year.


For m e d i u m and l a rge r t r e e s , t he following ra t ings were used f o r female flower and f r u i t crops:

Flowers o r cones per t r e e Rating

10 Very l i g h t 10-50 Light

50-100 Medium 100-400 Heavy

Over 400 Very heavy

Actual counts were made only on some of the t r e e s used i n controlled pol l inat ion work. I n P. s trobus t he ra t ings were approximately t h e same fo r t r e e s of a l l s i zes , but i n other species an allowance was made f o r s ize .

I n near ly a11 species there were so many instances of heavy morta l i ty between flowering and cone ripening t h a t the s i ze of t he f loyer crop was not a useful ind ica tor of s i z e of cone crop, Data from control-poll ination work show t h a t i n almost no case was cone morta l i ty due t o lack of po l l i - nation. Nor was it due t o obvious environmental factors-- except f o r some t r e e s of P. densi f lora and P. g r i f f i t h i i , i n which t h e flowers were damaged by insec t s .

( ~ u r i n g the period of observation covered by t h i s report , the author assumed t h a t the white pine weevil attacked the cones of P . strobus only during the second year, a f t e r the cones had enlarged appreciably; so weeviled cones were counted as sound i n est imating heaviness of f ru i t ing . How- ever, i n l a t e r observations--in 1952 and 1953--conelets dead and dying ea r ly i n t h e i r second year were examined on planted t r e e s near Philadelphia and on wild t r e e s i n the Pocono Mountains. A l l conelets examined had suffered weevil damage and soon dropped. I n the areas worked, cone crops were nil i n both years even though about half t h e t r e e s had flowered heavily. Yet control-poll inated branches t ha t were continu- ously protected by sausage casings did mature cones. It

PINE (PINUS)

BANKSIANA BUMEANA DENSFLORA FL EXILIS GRlFFl fHll STRORUS -

F i g u r e 8 . - -Flowering (white bars ) and f r u i t i n g ( b l a c i b a r s ) o f i n d i v i d u a l p ine trees.

appears t h a t i n this species t h e weevil i s t he pr incipal cause of cone-year periodicity--at l e a s t i n eas tern Pennsyl- vania. These l a t e r observations did not change the conclu- s ions reached f o r o ther species.)

Most pine species a r e generally regarded as bearing heavy f r u i t crops a t i n t e rva l s of 2 or more ye&ib:i, mi% l i g h t crops o r no crops a t a l l i n intervening years. This i s not t he pa t te rn exhibited by most pine species i n Phila- delphia ( f i g . 9). More apparent i s a tendency f o r c e r t a in t r e e s t o maintain heavy cone production year a f t e r year.

O f the species included i n f igure 9, only P. m i f f - i t h i i has what might be ca l led a "seed-yearv pat tern; and this i s not noticeable i n t he two young t rees . A llseed-yearn pa t t e rn w a s a l s o observed i n P. resinosa. This was not included i n the f igure because before 1951 observations were l imi ted t o a few t r e e s (d i f fe ren t each year) t ha t were flowering. I n 1951, however, a11 t r e e s of a l a rge group produced heavier cone crops than were noted on any of t he t r e e s i n the previous 4 gears

The tendency fo r c e r t a in t r e e s t o f r u i t heavily con- s i s t e n t l y has been noted by others i n s tudies of Scotch pine (l2) and l ob lo l l y pine (Q),

With few exceptions, t r e e s t h a t f r u i t e d wel l i n off years a l so f ru i t ed wel l i n on years, Most of t h e except.,ans were P, strobus: some t r e e s t h a t had f ru i t ed consis tent ly from 19&7 through 1950 f a i l e d t o f r u i t i n 1951, although some otherwise poor performers f ru i t ed well t h a t year.,

Rela t ively few observations were made on the phtt,ern of male flowering. Most hard pines and la rge P. g r i f y i t h i i seemed t o po l l ina te heavily each year. B u t i n P. s trobus, P. parvif lora , P. c a b r a , P, monticola ( 1 t r e e ) , and young t r ee s of P. g r i f f i t h i i , P. densiflora, P. sy lves t r i s , and P. koraiensis male flower crops did not occur annually--nor i n t h e same years a s t he female flower crops.

P r a c t i c a l A $ $ l i c a t i o n

Two years1 casual observation i n Western S ta tes in- d icates t h a t t h e ear ly f r u i t i n g of pines i n t he West i s not maintained i n l a t e r years by Insignes, Lariciones, and Stro- b i , t h e groups t h a t a r e adapted t o t h e Northeast. Austrian pine seems s l i g h t l y more f r u i t f u l i n the West and P. strobus i n the East. But t he di f ferences a r e much smaller than i n t he spruces. For t h e present more a t t en t i on should be given t o "vegetative climatef7 than t o "cone-producing climate" i n es tabl ishing breeding arboreta and seed orchards.

PINE (PINUS)

k(NKSUN.4 BmEANA CEMIRI OENS'SIFL ORA FLEXILIS GRIFFITHII 6RfFFlTW XORAIENSIS N 1 W PO FEET PO-30 FT. R - 4 0 F I P O - I S F X PO-SOFT. $0-30 FX SOFT. 20-30 F r PO-3OF%

I SUMMARY. ALL TREES

Figure 9 . - - F r u i t i n g records f o r ind iv idua l pine t r e e s .

28

N16RA P. S O F L I

PIN

S T R O B U S PO-40 F r

'US SSlLVEST L PO-so1

SUM IMARY, ALL T REES

However, seed y i e l .s h p o I n strobus g ie ld per cone i i n t h Ladelph area than in other parts of the speclttsf rang ,d y i e l a r e a l so low i n P. parviflora, P, f l ex i l i s , and cer tain t rees of P. n r i f f i t h i i . Seed orchards of these species should not be established i n the Philadelphia area. I n other species seed yields a re adequate a.

Y

Breeding arbGreta f 5 t o 10 times as many t rees as are needed f ents; fewer t r e e s a re needed f o r t h e Laricion Judging by figure 9, any 3 years1 (or possibQ observations of f ru i t ing behavior would be as gooa E

t o 5-year record f o ~ a t ing fruitfulness.

d per (

.s much :one i lower

-- - - C --

r tan t , e Phil e. See

. f t& pc

'or the

;ion.

pines shoulc - 1 conta - white ---- - A or fea

es and r only

Frui t ing observauons d g h t almost be -uc; rvlur, v

e d m t i o n i n l a t e sprin sn the previous yea r t s con are st111 on the t r ee or on the ground, the prese

_ yea r f s cones are e n l a r a , ,,A the present year 's flowe are present. I n E with 1 ,ent cones the task especially simple f at ion : ' ruit ing behavior f several years past. - - 'ever, tnt: p r s i s t e n t cones usual Lead t o an overestimate of fruitfulnese

A"

i s 'or . l ~

- species examin

How

?ersis i shows f L L - --I

~ f t h few exceptions (mostly P. strobus), t rees t n f rui ted best throughout t h sr period a lso frui ted we i n the on gears. Therefo s seed orchard a prelimina cul l ing fi the s p r h g a f t 2n yeas would eljminate t t a l l y unfrui t ful t rees , a econd c in an off ye would eliminate the l eas t ul tree

One scheme fo r mass-proaucing h y ~ l l a seea c a l l s f interplanting selected male and female elones. This appea feasible i f e i the r P. stsobus o r Po sylvestr is i s wed t he female parent, f o r i n both species there a r e enough e sent ia l ly female clones--at l e a s t i n youth- seed with l i t t l e contamination by selfing,

The same may also be t r u e of young P. g r i f f i t h i i and P. densiflora. However, most hard pines a r e suf f ic ien t ly male t o make such a scheme impractical (assuming f u l l se l f - ~ o m p a t a b i l i t ~ ) . In these 3.t appears necessar, t a r e of several cross-pollinating clones o hamd-pollination.

se a ni resort

P. strobus is such a poor p o l l k a t lea: Philadelphia area--that it seems advisa o use I c ies only as a female paren* fnr mass-proauction o i qeea the next 30 or 40 pears, Ld t r e ~ the si can be used as male parent

!s a l r e ady on

: R A I L C O N ; ' I O N !

There was a s l i gh t telescoping of t h e over-all f l c er ing season i n years when flowering s t a r t e d l a t e . Tk telescoping was l e s s marked than t h a t found f a r t he r north Canada (9. The telescoping was not equal f o r a l l speci or a l l port ions of t h e flowering season, because weath during a s wel l a s before the season influenced flowerin There P -ew instances i n which t he curves representi f lowe ri es f o r d i f f e r en t years crossed: t h a t i: son tha t ed ea r ly remained early.

rere f .ng da t ~t star

The spread i n flow within spec: g rea tes t i n t h e early-fl -es and ashes, spread var ied from 0 t o 2 ---I-- i n d i f f e r en t years.

*cad was associated 1 of t h the spx

re r i ng .merin,

time g - map' - - -.

r v G c n a . with 11

half I

ocatior

ies . M

Th MII-h

But i n a l l species ---- D r more of the spreau occu red within ra ther small groups of t r e e s . I n most speci extreme cases of ea r l iness o r la teness remained consta from year t o year, whereas t r e e s d i f f e r i ng by only a f Aays of ten sh i f t ed t h e i r r e l a t i ve order i n f l owerinl

f i n g v

? *

ras not Dichogamy su f f i c i en t t o preclude s e l 3nly i n some maple species, i n which t he precocity of ma D r f,emale flowers on a given t r e e tended t o remain consta from year t o year. For o ther groups there a r e few data the constancy of the s l i g h t dichogarqy observe-

henolo, l.. .I-&-

Lata f o I---- - ulua a ~ - e a ~ L I - c G U I I L ~ ~ L - G U WA l r ~ ~ ua lra I L - u r n lrrrr-GE: u ~JIIGL- Iuc;a ~ A U I J

4s t h e flowering season a t northern locat ions i s telescope me should expect t he di f ferences between locat ions t o g rea tes t f o r t h e e a r l i e s t s p e c i e - ~ This t rend i s obvio only f o r A . saccharinurn, t .est . For 1 species differences betwe bear l i t t l e t o flowering time.

he ver: e n loci

t ree of

rely 1; .owers I

i n eas, l t . Tten we

maple: , . ,.-

t o be 1 p a r t i vere mo

las

i s nf'

.-

.es

.nt 'ew

I n the s, and most hard pines male flower zrops tended LO we more common than female flower crops, and relat5v arge proportions of t h e t r e e s tended male f l annually. I n the spruces and f i r s , anc u l a r l y t e rn white pine, female flower crops P sbundar Male and female flowerinn uat terns f o r the sa

r e d i f fe ren t .

augar maple, t h e asnes, some oalcs, r e a plne, ana g r i f f i t h i i exhibited a strong tendency toward having ve yood and very poor seed years. I n other species a tenden for ce r t a in t r e e s t o bear consis tent ly h e a w o r l i g h t f ru

L* r Y CY it.

l o c a l i t : Table 2.--Number of days species i n t h r e e o the r

flower before (+) or a f t e r (-) t h e same spec i

i n t h e Philadelphia a1

sources: (2, &, 9 ) .

Place Cali

y tow2 be t te r - - - - - - -

crops was more pronounced than t he tendenc; years. Thus the t r e e breeder i s ap t t o get '

on t h e average by se lec t ing t r e e s ra ther than years. r e l a t i ve ly few exceptions, f r u i t i n g i n off years a f ined t o specimens t ha t made good showings i n other g

was li. ,he floi many P:

I

Species, i n order l r v i l l e , : n t r a l of f lowering .f ornia ;consin

Acer saccharinurn -- -13 t o -21 A . negundo -- + 2 t o - 9 A . platanoides -- 0 t o -10 A . saccharum -- - 3 t o -19 P i nus tabulaeformis + l U t o +26 -- P. banksiana +24 t o +41 - 1 t o -16 P. v i rginiana - 3 t o + 9 -- P. resinosa +19 t o +22 -- P. s y l v e s t r i s +19 t o +20 -- -l O t o -13 P . thunbergi i +29 t o +33 -- P. n igra +13 t o +16 -- P . bungeana +24 t o +32 -- P. f l e x i l i s +14 t o +27 -- P. g r i f f i t h i i +24 t o +25 -- P. s t robus +14 t o +21 --

t t l e mc Ner crc ines, a ----- -

ird see r e su l t

Wi t. ..- - ras con .ears.

I n the maples and spruces there between flower and f r u i t ; the s i z e of t e r n e d t h e s i z e o f t h e f r u i t crop. I n titularly i n t he ashes and Large flower t;rops n r e l i ab l e a s ind ica tors of L ru i t crops. I n fe was it possible t o determi ? cause of mortality forecast mor ta l i ty except by average performance of t ne t r e i n t he past .

f

Inzmany of t h e groupa, rGrformance of t h e t r e - :- off year gave a r e l i a b l e estimate of i t s performance 5-year period. Presumably se lect ion could be practice out recourse t o long-continued f r u i t i n g observations. --- nearly a l l cases a preliminary cu l l i ng i n an on year, fo l , lowed by another cu l l i ng i n an off year, would be qu i t e a, effect ive as cu l l i ng based on a continuous .5-year record.

r t a l i t ; IP gov md par lere un. !W case,

o r t~ . .

iG 2.11 a.

! over ;

!d with. 1 T1

L i t t l e cor re la t good seed years i n d i

was f o ~ n t spec

tween (

even t l

?elated and flowering a t t h e same time. Presumably any a t - ;empt t o co r r e l a t e f r u i t i n g behavior with weather conditions qould involve a minutiae of d e t a i l t o avoid a r r i v i n g at an

lat sui specie l y one

t f ulne a spruces, ana many pines. nos5 Grees 01 mese specl t t o f r u i t adequately i n a 5-year period. T h i s i s ar due i n l a rge p a r t t o genetic fac to rs , s ince nearly f r e e s observed were open-grown and vigownli-

Unf ruii -.-> -

.n suga - - - n

: S lalll

'parent: a l l t:

Unf ru i t fu lnes not been a ; ~ - u ~ - ~ ~ a n t breeding, two reasons. 1 1 L 3 b y IILUDU U L ~

plan t s a r e annuals o r short- l ived perennials . Natura t i o n has continually favored types t h a t produce see year. Second, t he f r u i t i t s e l f i s of value. Improvea r r u f 3een c ~ r i n c i p 1 , and n jide li

is has f o r

3us prc ...-.A r

.1 s e l e ~ !d eve

- A .

lulnes s )reedin

has 1 g work,

the I e ly a 2

a 1 objt ne .

But with t r e e s , na tu r a l se lec t ion has favore lulness only t o t h e extent t h a t a t r e e produces g several times during a long l i f e . There has bee

a r t i f i c i a l se lect ion.

With t r e e s , natura: ness much more i n specie, i n i t i a l ~ c c es sil long t o i a t i o n pine, sliver n--,--, poplars, ana --,, wmcn c lose ly I~LLL.. f i r e o r f lood and must have l a rge seed supplies ~n shor t notice, a r e much more f r u i t f u l than the suga e 9

beech, and oaks of t h e climax fo r e s t .

L selec n +hq+

'ruit f u: ; a r e cha r ac t e r i s t i c of tl

has fa^ rored f . . .

hose sj specit -LI -1.

3ecies ?s such

_-I ----I

t h a t bl

ready (

.r map11

Unfruitfulness presents a s e r i o mique p rob la It a l s o presents some broader imp l i ca t i The principi consequences of unfrui t fu lness are :

improvement program i s delayed. I n t he work of Northeastern Forest Experiment S ta t ion t he r e

e been numerous instances i n which it has been mposs ib le t o n r repeat a de :ross years, i n sp i t e seeming abund >f bree mater ia l .

us tecl ons .

lake o: ! o f a ,

s i r e d ( ance (

I n t h e nut t r e e s , t h e 1 Select ion f o r f rui t fulnc desi rable new varieti 'es,

Fruit ?ss w i l

i t s e l f i s i n demand. .1 i n i t s e l f r e su l t i n

There i s a probabi l i ty , not y e t t e s ted , t h a t exc s ive f ru i t fu lness and lack of v igor a r e associa t T h i s i s most l i k e l y i n t he oaks and other species which a l a rge f r u i t crop means a heavy dra in on t r ee . It may be t h a t t he se lec t ion f o r f r u i t f u l n necessary f o r control-poll ination work w i l l i n s e l f inva l ida te !nts ex: breeding.

- -

pec t ed any imj I rov eme

,-#

from

- -. a Eknphasis i s s h i f t e a away rrom desi rea ecviiurruc qu i t i e s . The numerical bas i s f o r selec-clun 1s reducc

ie popu ~ p u l a t i

A

1 t r e e prove

I roveme *,.- ....

Ejrtrapolation of t he resul crop-plant breedin( leads one t o believe t h a t most of a rac te r s believed tc be important i r bre edii :or, branchiness, pes t re. sistance--will died by multiple factors I f so, t he bq )y se lect ion within specie: w i l l depend on r;ne numuer or r;rees the se lec t ion i s basedon

t o be mnt pos: -.,- - .. - .

--- t he ess it- t h e

- 1

and g ,types

:enotypi w i l l bl

ng--vi g contrc

s i b l e 1: " *.----

. t s of t he ch

we cai 1 - - I - - - -

From populations of . 10, and 1,000 t r e e s ~ x p e c t t o recover individuais ~ . z d 6 , 2,330, and 3.1Go auovc

mean i n one character , O r , i f we consider i

L,000 t r e e s on which we pract ice se lec t ion fo: , L, ,, - 4 d i f f e r en t characters simultaneously, we cal expect t o recover t r e e s t h a t a r e 3,106, 1.86a, 1.286, 0:

0.926 above the population mean with respects t o those 1, 2 3, o r 4 c h a r a c t e r s . These f igures a p p l y t o phenotypes Since phenotype y impel l a ted , t he genc t o thi

e a r e e even

usual1 c loser

rfectly 3 mean.

his sel t r e e s z ~ n d s e l the phe

- L

i n pr ? best ibutior! ..&,.".A+

To i l l u s t r a t e how t works 'act lce Take a population of 2,000 . e c t thi 10 per cent from the upper end of . -distr : I curve I f the re i s a f a i r l y good currelablurl uetween ~ I I G I I V ~ ~ ~ ~ an( genotype, these 200 t r ee s w i l l a l l be from t h e upper end o the o r ig ina l genotype-distribution curve. By means of prog eny t e s t s the 10 percent giving t he best offspr ing r a n h selected from these 2 ent s . !OO par

- - - -

1 t r e e s

I f the species IS s u unf ru i t fu l tl-L, VIL _ percen of t h e t r e e s f r u i t , the original. population i s thus reduce t o 200 and the best 2 of 200 t r e e s have been se lected rathe than t h e best 20 of 2,000. And 2 t r e e s a r e not so firm foundation f o r a new v a r i e t

0 ) there )rmanc e

r, tht s t i l l may bc

9 f igor are 2C s s o s l

ousness of tk 1 selected par i g h t it camc

ke s e l e -ent s ; )t be m

ction (

but thc easurec

:an be s gain 3.

relaxel in p e r

f one f whicE

uy ro r f rui t2u~nes .s

popu: t f u l , ( . .

Lation of 20( me can selec.

.rac t e n , f o r ent i n

select i e f f i c i

- -.--L n ~ s u , AIL IUUGII III~~I-SP~CLIIC CIUSSIII~ wurk t he succes; : the *ark w i l l depe 3 t i nd i . th in the parent spe

mnd on : cies .

t he be: vidual:

a E f f e c t s

&&=a G a ~ * e four W ~ V S

n f o r 1

L I , -

rnf rui t

3 1.

A

lessen )e avoi

---,-sr; -cne Dreecung pro! ,o avo1 necess of se lec t ing f o r ~ l n e s s . With t n e oaks eve medium-scale con s l l i na t i on program would volve rigorous se n f o r f ru i t fu lness . This

and might inval idat c t ion f o r o t , With mater ia l c age f r u i t f uln ? f a r e a s i e r t o n -parent prog

t e s t s on 500 t r e e s than t o maKe 2-parent t e s t s 10 t r ee s . Although the 1-parent t e s t i s a much 1 precise measure of combining a b i l i t y than the n3-n-b t e s t , it would uncover a g rea te r amount

germ plasm among 500 than among 10 trc

n a in- i s

rious ac te r s , 3uld bc - -.. t on

ess 2- n f "I

ved - - - - precision of t h e 1-parent t e s t could be u p r - u considerably by planting t he preliminary pher~oty se lect ions i n such a manner t ha t a l l a r e subject po l l ina t ion by the same pol l inators . This appro mates the top-c

s i n which a sed a s t he ~ O L L ~ I L pc- ---- -

The I

I t e s t : s eve ra:

ing cox 1 stand

red nes liner

i s ur

?ars t h l i t i ng

uninarg t s a r e favora )ermane . t ion y

~ L W I - y e a r L,LJ ue musr; e1recr;lve. aucn ~ r u i t i n g w a s noted i n a few spruce t r ee s a f t e r t ransplant would not be very p r ac t i c a l i n a breeding program

Induce f r u i t i n g a r t i f i c j has been a great in te r t

' hern Europe. " - '

I n rec cent ye ed f r ~

e r e i n - - , induct

r re l : inducec must bt ---A - 1

& - m u &

, ing mu: l e of - t

2 ) . - Hoa s t be F repet i

? . . . I - m.

reve r, rtment : .LA L- ,

i f r u i t : capab " m _ _ l l - -

he t rea - -----

,a and llness . . seed I

T h i s re- ac-

e Locate breeding arboret gions of maximum f r u i t f ~

~ c h a r c i s con

t i c e i n agriculture, where seed production i s con- centrated i n lirnited areas known t o be favorable. A s yoted, cer ta in spruce species f r u i t much be t te r i n the West than i n the East. With further study, more examples can be expected where breeding arbo- retL and seed orchards should be located apart from the regions of vegetative t e s t ing and use.

"A*" V'

I not bl ~nsideri 1c-3 oes. i n ear:

seded F Larger stun u .- ---

L A alr .L

i s use reason _ 1- - - _ -

Increase the population on which select ion 1s w The number of t rees nl ,er species or per w i l l usually be much than can be handled the conventional arborc rith a vide spacing tween trees. However, most species will "+ l e a s t s t a r t t o f r u i t on a close spacing such as ordinary forest planting. There i s no the functions of +he +es t planting and the wee--, arboretum should e combined. I n a l l probabili ty there can be co able cul l ing f o r poor vigor, branchiness, an- ,--ti suscept ibi l i tv bv the time f ru i t ing s t a r t s nest.

md i n ! why di ne

C ' I 1

Anonwo us 1943. Arsber e 8veK

l ing a v ~ ~ o g s t r a h " = L A D

( A ~ E Foresl

fo r vt(xtf8rh under a r 1941 5 (2): ;ry Abs

Arn~org, T. 1946. Et t ps

stra rr lyck lnguler

rkringr -85.

ling oc

lf f i e l d 1947 and places ( .en collectior

; i tu te of Foresr, uwletics. Calj Res. Note 54

3f pol l - -L ,l-- 1 by t h .f. For

(4) Galrpern, G. U. 1949. Scots

e s t ~ pine i y Abst

n the I racts

bstract ) For

(5) Grant, Verne. 1949. Pollir

-i sngios pa-- r;volutlon 3 : =-Y'{. system: ng mec

A- --

nedic t The f l Amer

J o u

r.. S v r z .men, L. - , ,~ch. 1ploymh.t of species ; i n forestry. Dan 8 Col. Yearbook 1937

The en ual: Agr .

;, type; tish RI ' 151

s and i oy. Ve 4 PP*

(8) Le Aldo , A pher

t i e s , wisconsin, lY33-Iy43. m p ~ . 17: 81-122.

and Jo lologic - -.

nes, S< a 1 recc

Ira E l i 3rd for - -- -

.zabeth Sauk i .. - , - and Dar - - le Coun

.*

(9) Minshall, Wm. Harold, 1947. F i r s t dates of anthesis for four t r ees a

Ottawa, 0 t a r io , for the period of 1936 t 9 194';- canad. Field Nat - 61 5 56-59.

(10) Meehan, S. M. (n.d. ) Flowering times, the expected dates whe

t r e e s and shrubs w i l l bloom i n t h e Phila delphia area. E l l i s . Col, Arboretum. 8 p (Newtown Square, Pa. )

(11) Morris, R. F. 1951. Effects of flowering on fol iage productio

and growth of balsam f i r . Forestry Chron 27: 40-57.

(12) Pohl, F. 1939. On a form of Pinus s s l v e s t r i s t h a t flower

every year. ( In stwiss. Centb 61: 389-391.

1) For

(13) Pomeroy, K. B. 1949. Loblolly pine seed t rees : se lect ion, f r u i t

fu lness and mortal i ty. Southeast. Fores lk-pt. S ta . , Sta . Paper 5. 17 pp.

(u) Rehder, Alfred. 1940. Manual of cu l t iva ted t r e e s and shrubs.

996 pp. New York.

(15) ~ c h r g c k , Otto. 1949. D i e Vererbung der ~ r h b l i

~ k c h t e r 19 (8/9): 247-2 ite der ?54.

I Kiefe:

(16) Stout, A. B. 1938. The flowering behavior oJ

Jour. N. Y. Bot. Gard. ~7 ( 4 ~ ~ 1 ; LW-LJ+.

f Norwa nn / r L

(17) Wright, Jonathan W. 1952. Summary of tree-breeding expermencs by t k

Northeastern Forest Experb Statior 1947-1950. Northeast. Fores t. S t a , Sta. Paper 56. 47 pp., i l l u

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