Bryophytes Seedless Vascular

Plants

Gametophyte Free living, dominant,

photosynthetic

Free living, reduced life

span, usually

photosynthetic

Sporophyte Short-lived, dependent

on gametophyte for

nutrition

Long-lived, dominant,

independent,

photosynthetic

Limitations to

Life on Land

No vascular tissue, No

cuticle, Water required

for reproduction.

Water Required for

reproduction

Adaptations to

Life on Land

Cushion forming

growth; ability to

desiccate and hydrate

Cuticle, vascular tissue,

true roots and leaves

How to make your Holiday Tree last longer?

• Choose appropriate tree – Fir>Pine>Spruce>anything else

• Fresh Cut—Why?

• Fruit Baskets to kitchen

– Remove source of ethylene

• Lights

– White LED

– Leave lights on 8-10 hrs.

– Why?

Seed Plants

Gymnosperms & Angiosperms

• Sporophyte dominant

• Spores are retained on sporophyte

– Megaspores & Microspores

– Spores are no longer dispersed!!!!

• Gametophytes reduced greatly in size

– Microgametophytes—enclosed in pollen grains-no antheridia—one of two dispersal agents

– Megagametophytes—within ovules

• Seeds—second dispersal unit; contains young sporophyte with seed coat and food for young plant

Gymnosperms—Cone Bearing Plants Pine, Spruce, Hemlock, Fir, Larch, Cedar

• Needles—adapted to dry regions,

sunken stomates, thick cuticle and

reduced surface area

• Secondary growth—xylem with

tracheids

• Pollen cones--Microsporophylls

• Ovulate cones--Megasporophylls

• Terpene Chemistry

Gymnosperm Leaves

Pine as Representative

Very thick cuticle

Sunken stomates

Leaf Endodermis

Multi-layered skin

epidermis & hypodermis

Microspore to Microgametophyte

• Microsporophylls in pollen

cones are modified leaves to

hold microsporangia

• Meiosis in microsporangia

produces microspores (1N)

• Microspores are not

released from sporophyte

(2N)

Pollen as a Microgametophye

• Pollen grain is a four-celled

microgametophyte

• Dispersed by wind; air bladders

assist make pollen buoyant

• Pollination—pollen lands on

sticky droplets on ovulate scales

• Generative cell divides to produce

two sperm nuclei

Megaspore to Megagametophyte

• Megasporophylls are modified leaves of ovulate cone that produce megasporangia

• Megaspores are not released from sporophytes

• Megagametophyte forms after pollination and produces archegonia

The Seed Advantage

The embryo is protected in a seed coat

Megagametophyte provides

nourishment to developing seed

Seeds dispersed from maternal plant

completed with a young embryo

Living Fossils—Metasequoia glyptrostroboides

relative of Sequoia sempervirens

Metasequoia fossils were described in

1941 (200 MYA). In 1944, a Chinese forester

visited a village in a remote province of

southern China and discovered a temple

built around a single Metasequoia.

Later expeditions found a natural population.

Living Fossils-Ginkgo biloba Discovered in Chinese and Japanese Temples.

Pollution tolerant street tree

Deciduous

Rancid female cones

Ginkgo tablets in health

food stores

Economic and Ecological Value of

Gymnosperms

• Naval Stores—pine tar, turpentine,

resins

• Pulp wood for paper products

• Spruce wood for musical instruments

• Christmas trees—spruce, fir, & pine

Historical Value of Gymnosperms

• Gymnosperm resins are extraordinary

preservatives

• Amber—the only plant produced gem

– Preserves ancient insects, feathers, twigs,

& microbes

• Resins used for embalming mummys

Medical Gymnsoperms

• Ephedra-Mormon Tea – Ephedrine—alkaloid that is a

stimulant

• Taxol-arrests cell division by interfering with spindle fibers—cancer treatment

• Cycad poisoning on South Pacific Islands – Symptoms mimic parkinsonism

and ALS

Important Ecology of Gymnosperms

• Discovery of insect juvenile (molting) hormones

• Serotinous cones and fire adaptation

• Adaptation to severe environments

• Bird dispersal of some seeds

• The oldest and largest organisms

Gymnosperms

Gametophyte Greatly Reduced

Microgametophyte—pollen—4 cells—wind

dispersed

Megagametophye with archegonia becomes

nutritive tissue after fertilization

Sporophyte Long-lived, dominate life form

Limitations to

Life on Land

Very little—well adapted to many conditions

Adaptations to

Life on Land

Vascular cuticle, cuticle, pollen, seeds

Bryophytes Ferns & Allies Gymnosperms

Gametophyte Dominant Reduce, Free-

living

Micro & Mega

Greatly reduced

Micro-Pollen

Sporophyte Ephemeral,

dependent on

gametophyte

Dominant Dominant

Adaptations to

Life on Land

Cushion

growth

Vas. Tissue,

Cuticle, Stoma

Vas. Tissue,

Cuticle, Stoma

Water not needed

for sperm transport

Seed-provides

protection and

nutrition for young

sporophytes