Plant Reproduction (Terrestrial)

– nonvascular > vascular,

– haploid dominant > diploid dominant,

– homosporous > heterosporous,

– motile gametes > nonmotile gametes,

– seedless > seeds,

– water > wind and animals;

• gamete,spore and seed disbursement.

Trees

Bryophytes

Sporophyte:

• Cells are diploid (2n)

• Produces spores (n) through meiosis

Gametophyte:

• Cells are haploid (n)

• Produces gametes (n) that fuse to form a zygote (2n)

Sporophyte? Gametophyte?

Haploid Dominant > Diploid Dominant

Fig. 30.1

Homospory vs. Heterospory

• The principal difference between homospory and heterospory is the separation of sexes at different points in the life cycle,

– female gametes in ovules,

– male gametes in pollen grains,

• heterospory promotes outcrossing among plants, since microspores may drift farther from the sporophyte than megaspores.

Egg (n)

Zygote (2n)

Spore (n)

Maturegametophyte (n) Mature

gametophyte (n)

Developingsporophyte

Developinggametophyte

Mosses• nonvascular (mostly) • haploid dominant

• homosporous

• motile gametes

• seedless

• + water dependent

Simple, unbranched sporophyte dependent on gametophyte.

See Fig 29.16

Ferns• vascular • diploid dominant

• homosporous

• motile gametes

• seedless

• + water dependent

Branched sporophyte not dependent on gametophyte at maturity.

reduced, naked... Fig. 29.23

Sporophyte vs. Gametophyte

• self defense, anti-desiccant,

• large, branched sporophyte capable of producing more spores,

• diploid organism has a greater capacity for complex growth,

– two copies of every gene,

haploid

diploid

– mutation do not necessarily hinder development (i.e. one good copy and one mutant copy in a diploid).

w/ mutant gene

w/ mutant gene

Heterosporous“primitive”

• In these plants, a sporophyte produces two types of sporangia,

– microsporangia contain microspore mother cells, each of which undergoes meiosis, forming microspores,

– megasporangia contain megaspore mother cells, each of which undergoes meiosis, forming megaspores.

Selagenella

microsporangia

megasporangia

sporophyll: (phyll: leaf)

Gymnosperms

• vascular • diploid dominant

• heterosporous

• nonmotile gametes

• naked seeds

• not water dependent

Gymnosperm Seedsnaked embryos

Ovule (immature): megasporangium

“surrounded” by integument. When mature, an ovule becomes a seed.

Pollengymnosperms

• Outer layer of pollen is made impermeable by a cyclic

alcohol “sporopollenin” ,

– winged for wind dispersal,

– lots of pollen is produced, and randomly reaches the micropyle of receptive ovules.

Lodgepole pine

Pinus contorta

Angiosperms

• vascular • diploid dominant

• heterosporous

• nonmotile gametes

• seeds w/ 3n endosperm

• not water dependent

Monocots/Dicots

Monocot:• Petals are in multiples of three• Leaf veins run parallel• Vascular bundles in the stem are dispersed

Dicot:• Petals are in multiples of four or five• Leaf veins are branched• Vascular bundles in the stem are arranged in a ring

Corn is a fruit!

Types of fruit:

• Simple = single flower, single ovary

• Aggregate = single flower, multiple ovaries

• Multiple = multiple flowers, ovaries fuse together

• A fruit is a mature ovary that develops after the egg has been fertilized.• Each kernel is a simple fruit