Flower
-Petals attract pollinators
-Anther The part of the stamen where pollen is produced.
-Filament carry nutrients to the anther for the development of the anther and pollen grains.
-Stamen The pollen producing part of a flower, usually with a slender filament supporting
the anther.
-pollen tube transport male gametes toward the female gametes.
-Stigma part of the female reproductive system of a flower. It is found in the center of a
flower and helps to collect pollen.
-Style generates the pollen tube but also prevents incompatible pollen from entering the
ovary.
-ovary develops into the fruit and the ovules are formed into seeds.
-ovule female gametes have inside the ovules (site of fertilization)
-Carpel female reproductive organ of flowering plants and the development of diversified
types of fruits
-nectary attract pollinators, Nectaries are usually located at the base of the flower stamens,
which draw animal visitors into contact with the pollen to be transferred.
-receptacle The part of a flower stalk where the parts of the flower are attached.
-Sexual reproduction in flowering plants: Male gametes (in pollen grains) anther fuse with
female gametes (in ovules).
Self-pollination and cross pollination
Self-pollination Cross pollination
Transfer pollen grains from the anther to the Transfer pollen grains from the anther to the
stigma of the same flower. stigma of a different flower.
Self-pollination increases genetic uniformity Cross-pollination decreases genetic
and decreases genetic variation. uniformity and increases genetic variation.
Single plant Two different plants of the same species.
small number large number
Insect pollination
Insect-pollinated plants use insects and other animals to carry their pollen grains to other
plants.
-Stigma Sticky to allow pollen on insects to attach
-has brightly colored petals, strong scents and nectary
-mutualism a type of symbiotic relationship where all species involved benefit from their
interactions. flowering plants gain an opportunity to reproduce
-Enclosed within’ the petals
- insects gain a food source (pollen, nectar) from plants
-pollen grains large, sticky/spiky and small number of pollen grains
Wind pollinated flower
- Wind-pollinated plants let their pollen blow in the wind and hope that their pollen grains
reach another plant for pollination.
- stigma feather like structure to trap pollen passing by in the wind
- anther The anthers may produce a large number of pollen grains.
- pollen grains small, light, and produced in large number so a lot of wastage occur.
- anther exposed to the wind
- do not have nectar, do not have strong scents to attract to insects
Wind pollinated and insects pollinated differences:
Insect pollinated flower Wind pollinated flower
Brightly colored to attract insects No bright colors, special odors, or nectar
Enclosed within the flower so insects must Stamens and stigmas exposed to air currents
make contact
Have strong scents and nectar Do not have scents and nectar
Pollen Larger, sticky Pollen smooth, light, easily airborne
Stigma Sticky, so that pollen attaches to Stigma Feathery, to catch pollen blown from
insects wind
-The ovary become the fruit a structure that contains seeds; fruits develop from ovaries after
fertilization, and often help the seeds to be spread away from the parent plant.
-The ovule become the seed a structure that contains an embryo plant, and food stores to
help it to begin to grow into new plant.
Seed formation
A seed is formed when fertilized ovule divides by mitosis. It stores food and has the
potential to develop into a new plant under optimal conditions. Fertilization is the process of
fusion of male gamete and female gamete to form a zygote.
The zygote starts to divide. It produces a little group of cells an embryo. This embryo
will eventually grow into a new plant. The ovule also begins to change. It gradually grows into a
seed.
-Plumule To become first shoot
-Radicle become first shoot
-cotyledon food stores
-seed coat protective layer
-micropyle a minute opening in the integument of an
ovule of a seed plant.
-Testa the tough outer coat of the seed.
Methods of seed dispersal
-Seed dispersal process by which seeds are dispersed to distant places by agents.
Abiotic agents
-By wind
Devices such as wings, hairy, popups and leathery styles make the seed or fruit easily wind-
borne. Example: Dandelion has parachute and hair like structure, light weight.
-By water
Seed and fruits develop floating devices like spongy or fibrous outer coats. Example: coconut
-By Explosive
Fruit with pods continuing seed burst on their own. Seed are provided with values at jaculates
(curved hooks) which help to scatter seeds with a jerk. Example: Lupin, balsam and beam pods.
Biotic agents
-By animals
Seeds and fruits process hooks, bards, spines, bristles by which they adhere to bodies of
animals. Example: berry, nuts and martyria
Why is seed dispersal?
-To avoid competition for sunlight, water minerals, and space between parent plants, and
new plants.
-to produce healthy new plants.
