Plant Bio Day 2

1. Alternation of generations & life cycles in general 2. Division Bryophyta (Mosses) 3. Division Pterophyta (Ferns etc.) 4. Homospory vs. heterospory 5. Division Coniferophyta (Conifers)

In land plants, meiosis produces _

Spores

Spore

Single cell that can divide to produce multicellular organism

Gamete

Single cell that can unite w another gamete to produce a diploid zygote

Embriophytes

10 divisions, 4 major: moss, fern, conifers, angiosperms

Moss

* Low growing
* Confined to damp areas
* Swimming sperm
* No true vascular tissue (rudimentary vascular system)
* No true leaves
* **Gametophyte dominant** 
* Homosporous (1 spore size)

Ferns

* \~400 mya
* Vascular tissue
* Xylem & phloem
* Support & supply
* Swimming sperm
* **Sporophyte dominant**
* Homosporous or heterosporous

Fern life cycle

Sporophyte grows out of gametophyte and gametophyte goes away

Homospory

1 size of spore from meiosis

Heterospory

2 sizes of spore from meiosis

Megasporiangium

Female

Microsporangium

Male

5 divisions (phyla) seed plants

* Cycadophyta
* Ginkgophyta
* Gnetophyta
* Coniferophyta
* Anthophyta

Seed

Embryo + nutrition (megagametophyte in conifers) + Seed coat

Seed development

* Develops from ovule
* Novel structure appearing in seed plants
* Site of female meiosis
* Contains female gametophyte, sex organs, egg, & embryo

Diploid conifer @early stage

Integument

Megasporangium

Haploid conifer @early stage

Megaspore

Megagametophyte

Pollen

Mature male gametophyte

Conifers

* Reproductive organs in cones
* **Sporophyte dominant**
* Heterosporous
* Microgametophyte = pollen!
* Megagametophyte
* within ovule
* makes egg & then nourishes embryo

Sporocyte

* Single cell that undergoes meiosis to make spores

Where is integument

On outside

when does pollination happen

BEFORE female meiosis

Megagametophyte

* Makes egg in archegonium
* Nourishes embryo

Microgametophyte

Pollen grain (makes sperm)

Phylum coniferophyta (fir, pine)

* Seeds & pollen
* Cones: separate male & female
* Naked seeds: “gymnosperms”
* Seed = embryo nourished by mega-gametophyte
* Slow reproduction