Chapter 30 Seed Plants

Soft Wood

Polypodiophyta (and relatives) and Gymnosperms have only tracheas in their xylem

Hard Wood

Angiosperms have tracheas and vessel elements in their xylem

Evolution of Seed plants

evolved from spore-bearing plants known as progymnosperms about 400 MYA

Success atrributed to evolution of seed

• protect developing embryo

• provide food for embryo

• capable of dormancy in unfavorable environmental conditions

Cotyledons

provide food for developing embryos

Testa is the

seed coat that protects developing embryo & stored food

Seed Plants area also known as

Spermatophytes

Seed is made of

embryo (young plant) + cotyledon(s), +- endosperm

Gymnosperms contain

3 or more cotyledons

Angiosperms are also known as

Magnoliophytes

Angiosperms contain

one cotyledon (Monocotyledon) or two (Dicotyledon)

Monocotyledon

one cotyledon

Dicotyledon

two cotyledons

Gymnosperms refer to the

naked seeds

Seeds in Gymnosperms

seeds produces on the surface of sporophylls or similar structures, instead of enclosed within a fruit

Sporophylls

modified leafs

• seed-bearing and pollen-bearing sporophylls often arranged in cones or strobili

Seed in Angiosperms

• developed from fertilized ovule contained in fruit

• Ovule contained in ovary

• Ovary forms the fruit

Heterosporous

produces two distinct types of spores

• Spermatophytes are Heterosporous

Microspore

• Forms the pollen grain

• Produce sperm in male gametophyte (Microsporangia)

• Dispersed by wind or a pollinator

Microsporangia

the male gametophyte and contains microspore (pollen)

Megaspore

• Develops in ovule

• Forms the female gametophyte (Megasporangia)

• Contains the egg and polar nuclei

Megasporangia

The female gametophyte and contain the megaspore

Gymnosperms includes the phylums

Pinophyta, Cycadophyta, Gnetophyta, Ginkgophyta

Angiosperms includes

Magnoliophyta (Anthophyta)

Phylum Pinophyta (Conifers)

• Most common gymnosperm phylum; includes pines, spruces, firs, cedars

• Found in colder & sometimes drier regions of the world

Pinus

• Leaves needlelike and arranged in clusters of two to five leaves

• Most common Gymnosperm

• soft wood (xylem with tracheids only)

• Thick cuticle and recessed stomata

• Resin canal

Resin

is antiseptic and aromatic, prevents development of fungi, and deter insects

Female Cone: Ovule has

• Integument

• Nucellus

• Micropyle

Integument

for protection and forms seed coat (testa) after fertilization

Nucellus

provides nutrition

Micropyle

a hole in the Megaspore where sperm enters

Phylum Cycadophyta (Cycads)

• Small unbranched trunk surrounded by crown of leaves

• Male and female reproductive structures in center

• Slow-growing gymnosperms

• A mix between a fern tree and a palm tree

Phylum Gnetophyta (Gnetophytes) contains 3 diverse genera

• Welwitschia

• Ephedra

• Gentum

Genus Ephedra is under the phylum

Gnetophyta

Ephedra produces

drug ephedrine used to treat respiratory problems,, now replaces with synthetic drugs as it causes strokes and heart attacks

Phylum Ginkgophyta only has one living species

Ginkgo biloba

Phylum Ginkgophyta are

• Dioecious

• And smell

Dioecious means

Male and female reproductive organs are on different plants; aka there are male and female trees

Ginkgo trees:

male, as seeds of female trees produce foul smell

Phylum Magnoliophta (Angiosperm) are

The Flowering Plants where are very diverse due to differences in reproductive structures. It only has one phylum

Characteristics of Magnoliophyta

They produce flowers and fruits, their seeds are enclosed also surround by Endosperm, and do double fertilization

Endodsperm

a nutrient package that surrounds the developing embryo of a Magnoliophyta

The pedicel

where the flower is attached to stem by stalk

Receptacle

Pedicel expands at the tip, to which other parts attach to

Ovary are made up of

the Ovule and Ovary wall

Flower Whorls has 3 sections

• Outermost - Sepals

• Second - petals

• Third - Stamen

Whorls

Flower parts are organized in circles. There are differences between Monocts and Dicots

Monocts Whorl

whorls of three flowers, or multiples of three

Dicot whorls

whorls of four or five flowers, or multiples of four or five

Stamen is

male reproductive stricture

Each Stamen (androecium) has

pollen-bearing after & a filament (stalk)

Anther produces

pollen

Pollen forms the

male gametophyte which contains sperm

The Pistil is made up of

The stigma, style, and ovary

Stigma is

the tip where pollen lands

Style is

the stalk where pollen tube germinates

Ovary is the

swollen base containing the ovules

Ovary later develops

into a fruit (after fertilization)

The outmost whorl is

Sepal

The pistil houses

the female gametophyte which contains the egg

Ovule contains

female gametophyte which contains the egg, and later forms seed after fertilization

Double fertilization

is a feature of Angiosperms

Self-pollination

transfer of pollen from anther to stigma of a same plant

Cross pollination

transfer of pollen from anther to stigma of a different plant of same species

Germinate is

the formation of a pollen tube

Pollen tube comes from

The pollen and grows through the stigma and style to enter the micropyle

Male gametophyte produces how many sperm?

Two

Double fertilization where

One sperm unties with egg to form the diploid zygote

• New sporophyte

Other sperm unites with the two polar nuclei of central cell to form the triploid endosperm

• provides nutrients to embryo

Fruits develops

from flower ovaries after fertilization and contain naked seeds

Pericarp

the outer wall of the fruit

has three layers: exocarp, mesocarp, endocarp

Pericarp develops from and is

the ovary wall

Exocarp is the

skin

Mesocarp is the

flesh

Endocarp is the

pit, which is the wooden shell that surrounds the actually seed

Radicle is the

part of the seed where first emerge and form roots

Specific Germination adaptations

some adaptations ensure that seeds will germinate (grow) only under appropriate conditions