Plants (Flowers, Fruits and Seeds) Unit 3 Plants (Flowers, Fruits and Seeds)

Flowers

Question? How are flowers like Humans?

Function of Flowers Reproduction Attraction Attract Insects for pollination Attract animals for seed dispersal

Structure Stalk – holds up the flower Receptacle – swollen tip of a branch Sepals – surround and protect the developing flower a. Outer most Whorl (circle) Petals – brightly colored for show Next whorl

Stamens – male reproductive structures 2 parts Anther – swollen tip that contains microsporangia (pollen) Filament – supports the anther Carpels – female reproductive structures Can be one or more fused together

Pistil – the carpel(s) of the flower Made up of Ovary – enlarged base of pistil Style – stalk like raise from ovary Stigma – upper tip of pistil that is sticky or has hairs to trap pollen 8. Some flowers have both Stamen and Carpels, some only have one or the other

Perfect Flowers – have both stamen and carple Imperfect Flowers – only stamens or pistils not both Ex: Pine trees Pistillate cones - on top of tree (Female) Staminate cones – on bottom or tree (male) Perfect flowers: dandelions, roses, daisies, cherry blossoms Imperfect flowers: squash, cucumbers, pumpkins, grass Willow, Oak and corn

Fertilization (pollination) The Pollen (sperm) must get to the egg in the ovary of the pistol How? Pollen is a 2 nucleated cell Generative nuclei – fertilizes the egg Tube nuclei – creates a tube to the egg How it happens:

Types of Fertilization Insect Pollination – ex: bees Colored parts, Fragrance, Nectar attract insects insect then carry pollen to other flowers and pollen rubs on the stigma Water Pollination Water carries pollen to other flower

Ways to prevent self pollination Wind Pollination Plants with many pollen grains for greater chance Wind carries pollen to other plants Ways to prevent self pollination Imperfect flowers Short stamens Stamens hang below Different ripening periods for male and female parts

Fruits

Fruit – a matured ovary of a flower Function: Protects seeds Seed dispersal Taste good so animals eat them Carry seeds away from plant Release them

Types of Fruit Simple fruits: Complex (compound) fruits Dry or fleshy Result from one pistil of a single flower Ex: Peas, grains Complex (compound) fruits More complex fruit body More than one pistil of a flower fertilized Ex: Pineapple

Legume – fruit that splits along 2 sides ex: Peanut, beans, peas

Follicle – Splits along only one side ex: Milkweed

Nut – thick woody ovary wall ex: Oak or Chestnut

Achene – thin ovary wall - most common Ex: Sunflower Buckwheat

Samara – seeds much like achene’s with a thin flat wing attached Ex: Box elder seeds, or elm seeds

Drupe – seed with a stony inner layer around the seed Ex: Peach, Plum, chokecherry

Pome – core with seeds surrounded by a papery ovary wall Ex: Apple

Berry – thin skin with many seeds Ex: Tomato

Pepo – berry with a thick, hard rind Ex: cucumber, pumpkin, melons

Hesperidium – berry with leathery skin Septate – divided into parts Ex: Oranges, grapefruits

Aggregate Fruits – several pistils of one flower with clusters of small fruits Ex: Raspberry

Multiple Fruit – several flowers growing together to make a fruit Ex: Pineapple

Seeds

A. Parts of a Seed 2 layers Seed coat Endosperm – stored food like a yoke of an egg

B. Embryo anatomy 1. Monocot Dicot Plumule – first single leaf of a seed Endosperm – stored food Radicle – first root Dicot Cotyledons – First two leaves of a seed

Germination Hypogean – seed stays below ground a. Monocot Plants Epigean – seed is pulled above ground Seed splits and cotyledons are first leaves Dicot plants

Methods of seed dispersal Mechanical – exploding pods Wind Samara – dandelion Tumbleweeds Animals Burrs Feces Water

End of Chapter Notes