First Seed Plants

- bear exposed seeds "naked seeds"

- heterosporous

  - dioecious

First flowering plants

- dominant sporophyte stage

Gymnosperm

reproductive components

- exposed seeds on prominent strobili or cones

- strobili have shortened stem with sporophylls that bear sporangia

- sporophylls with mircrosporangia= mircrosporophylls

- megasporophylls bear megasporangia

- male microspores

- female megaspores (separate cones)

male cones

typically much smaller

ovulate

female cones

(much larger)

"two houses"

male and female parts are borne on separate plants

female gametophyte: handful of cells buried in tissues of the sporophyte

male gametophyte: pollen grain

brief free-living stage

carried via water, wind, animal

- the ovule (megasporangium + megagametophyte + integuments)

- nutrient tissue (food supply)

- sporophyte embryo

microsporocyte (diploid)

- meiosis X 2

- 4 haploid spores

microgametogenisis

released mircospore ->

polarized microspore ->

Pollen Mitosis X 2

Tricellular Polen 

fertilization (2n)

seed -> sporophyte -> micro + macrosporangium

meiosis (1n)

micro + macrospore

micro (pollen) + macrogametophyte

sperm + egg

fertilization

zygote (seed)

Gymnosperms

Phylum Cycadophyta

kyos: palm   phyton: plant

200spp

Looks like a palm tree

seeds are toxic

ex: Cycas revoluta, Zamia

Gymnosperms

Phylum Ginkgophyta

gingko: silver apricot

1 spp. 

Gingko biloba

(only living spp)

- dioecious

- mircosporangia: pollen grains

- megasporangia: seed covered with a thick fleshy shell

- seeds stink, not a fruit

- leaf extract used to treat asthma + multiple sclerosis

- leaf two-lobed

Gymnosperms

Phylum Coniferophyta

conus: cone   ferre: to bear

630 spp. 

largest group of gymnosperms

pines, spruces, cedars, firs, hemlocks, yews, redwoods, cypress trees

adapted to cool, dry climates

special tracheids (narrow)

swamps, dry mountain regions

water conducting cells

the narrow tracheids of conifers

- improve capillary action

- less susceptible to breaking in freezing temp.

bald cypress

swamp cypress

cypress kneeds

- mo oxygen

- stablization

Dawn Redwoods

common around universities

seasonally shed leaves 

- metasequoia

- bald-cypress

- genus Podocarpus

- not a yew

- dioecious

- male cones are tiny, clustered together

- female cones: one green seed with an aril

(modified fleshy scale, looks like a berry)

Gymnosperms

Phylum Gnetophyta 

71 spp. 

produces four haploid megaspore

3 of these degenerate, the 4th germinates into the female gametophyte

contains 2 archegonia 

each with a single egg

the megasporangium is covered with a layer of protective cells - the integument with a tiny opening (the microphyle) where the pollen tube will grow into the megasporangium 

layer of protective cells

surrounds the female gametophyte

tiny opening where pollen tube enters

pine cone

contain sporangium 

produce pollen grains

2 microsporangia, microspore + mother cells 

produce haploid pollen grains

Angiosperms

Phylum Anthophyta

anthus: flower

Flower plants

Class Monocotyledonae

Class Dicotyledonae

Angiosperms

Phylum Anthophyta

Class Monocotyledonnae 

mono: one  cotyl: cup

- one cotyledon

- floral parts in threes

- parallel leaf veins

- pollen grain has one pore or furrow

- vascular bundles throughout stem ground tissue

Angiosperms

Anthophyta

Class Dicotyledonnae 

di: two  cotyl: cup

- two cotyledons

- floral parts in 4 or 5s

- netlike leaf veins

- pollen grain has three pores or furrows

- stem's vascular bundles arranged in a ring

- faster growth

- greater seed production

- vessels + tracheids

- flowers: reproductive structures

- seeds enclosed in fruit > greater dispersal

- diversity: shape size, type of leaves

fruit!

- oranges, melons, peppers, cucumbers, tomatoes, olives, nuts, etc

attached to pedicel

bears organs of the flower

outermost whorl of leaf, petal-like, encloses flower

form calyx

above sepals

form corolla

male part

androecium

top of stamen

contains pollen grains

female part

gynoecium

leaf modified to hold seeds

(stigma, style, ovary)

tip of the pistil

where pollen grains land