seed plants

when did flowering plants begin to diversify?

mesozoic era

when were the first seed plants?

paleozoic era

four types of gymnosperms

1. ginkgophytes

2. cycadophytes

3. gnetophytes

4. coniferphytes

ginkgophyta tree

Ginkgo biloba

cycadophyta

fern-like or palm-like fronds radiate from central stem

example of cycadophyta

Sago Palm

gnetophytes

3 distinct genera, male & female strobili; sperm not motile

example of gnetophytes

Ephedra

conifers

biggest group, “cone-bearers”

angiosperm derived characteristics

flower & fruit

purpose of the flower

protects ovules within ovary

how do flowers promote pollination?

makes sugar water that makes pollinators look for the same type of flower

purpose of the fruit

enhances seed dispersal and protects dormant seed

unisex flowers

considered incomplete

inflorescence

group of flowers that is more attractive to visual pollinators

coevolution of plants & their pollinators

plants: selection for displays & scent that attract visitors

pollinators: selection for senses/anatomy that help locate flower & get reward

what is fruit derived from?

ovary tissue after fertilization

fleshy fruits

adapted to be eaten by animals seeds

dry fruits

help dispersal by wind, water, or animals

angiosperms: double fertilization with 2 sperm nuclei

• one fuses with egg, forming zygote (2n)

• one fuses with 2* central nuclei, forming endosperm (3n*) food supply in seed

why phylum includes all extant angiosperms?

phylum Anthophyta

three basal angiosperm clades

1. amborella

2. water lilies

3. star anise

magnoliids clade

magnolias and relatives

monocots

• 1 cotyledon

• parallel veins

• scattered vascular tissue

• fibrous root system

• groups of three

eudicots

• two cotyledons

• netlike veins

• ring vascular tissue

• taproot usually present

• multiples of four or five

heterosporous

megaspores & microspores

megaspores

grow into female gametophytes

microspores

grow into male gametophytes

mosses and other nonvascular plants gametophytes

only category where gametophyte = dominant

gymnosperms and angiosperms gametophytes

reduced, dependent on surrounding sporophyte tissue for nutrition

ovule

the megasporangium w/ retained megaspore + surrounding sporophyte tissue

pollen

microspores retained; mature into pollen grains while within microsporangium

pollen grains

mature male gametophytes with sporopollenin protective coating

pollen tube

grown by pollen grain toward egg within ovule

seed

develops from fertilized ovule

what does a seed include?

embryo, food supply, seed coat

seed coat

came from integument, safe from desiccation