Lecture # 14

Mosses: (1) do not produce seeds;
(2) the conspicuous plant is haploid;
(3) the haploid plants can reproduce asexually;
(4) the haploid plants are male and female;
(5) show alternation of generations

Water is required for fertilization.

Foot, seta and capsule of the sporophyte

Angiosperms produce seed inside a fruit.

A flower is a modified stem carrying modified
leaves arranged in whorls.

Whorl              Components

calyx                sepals

corolla             petals

androecium    stamens

gynoecium     carpels (pistils)

stigma, style and ovary

Hermaphrodites have both male and female
components on one individual.

self-fertile

self-sterile

self-fertilization

cross-fertilization

complete

incomplete

perfect

imperfect

A imperfect flower is always an incomplete
flower but a perfect flower is not necessarily
a complete flower.

staminate

carpellate (pistillate)

monoecious

dioecious

Pollen is produced in the anthers
from microspore mother cells.

pollen grains

Egg cells are produced in the ovule
from megaspore mother cells.

8 haploid nuclei in 7 cells

The transport of the pollen from the anther
to the stigma is pollination.

The pollen tube grows down the stigma
and style to the ovary.

vegetative nucleus and sperm nuclei

The fertilized egg is the zygote.

Endosperm is triploid.

double fertilization and triple fusion

radicle, stem and cotyledons

monocotyledon (=  monocot)

dicotyledon (= dicot)

The ovule develops into the seed.

seed coat or testa

The ovary develops into the fruit.

Fruit is used for seed dispersal.

Plant embryos become dormant.

Seeds must be activated to germinate.

The most certain sign that a seed is germinating
is the imbibition of water.

The radicle almost always emerges first.

hypocotyl

epicotyl