Angiosperm ~Flowering plants~

World’s Largest Flower Rafflesia, the stinking corpse lily diameter up to one meter and can weigh up to 10 kilograms discovered in the Indonesian rain forest

General Characteristics Flowering plants Reproduce sexually through flowers – Process: pollination Seeds are covered in a fruit

General Characteristics Most widespread of land plants Over 250,000 species 2 subclasses – Monocotyledonae (monocot) ie. Corn, wheat, lilies, orchids – Dicotyledonae (dicot) ie. Tomatoes, daisies, roses Pear tree

Monocot vs Dicot Cotyledon: seed leaf, primary embryonic leaf within the seed in which nutrients for the new plant are stored – one in moncots – two in dicots dicot monocot

Fibrous rootsTap root

Vascular Bundles in Roots Monocot -circular arrangement Dicot -Single mass of Xylem that makes an X in the middle -Phloem is between xylem

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Structure of Angiosperms Petal Sepal Anther Stigma Ovule Ovary Stem (recepticle) Style Filament (♀)(♀) (♂)(♂) Pistil Stamen

Angiosperms Complete flowers have sepals, petals, stamens & pistils

Angiosperms Complete flowers have sepals, petals, stamens & pistils

Angiosperms Complete flowers have sepals, petals, stamens & pistils

Ovules Angiosperms Complete flowers have sepals, petals, stamens & pistils

Bisexual flowers have both male (stamens) and female (pistils) reproductive structures; so complete flowers are also bisexual Angiosperms Complete flowers have sepals, petals, stamens & pistils

Angiosperm: Pollination Transfer of pollen from an anther to a stigma & Double Fertilization

Pollination 2 types: – Self-pollination: pollination within the same flower – Cross-pollination: pollination between 2 flowers Wind-pollinated plants – pollen grains fall and carried by wind – flowers are small and plain with little fragrance

Pollination Animal-pollinated plants (“vector pollination”) – Plant provides nectar (good source of glucose) – animals picks up pollen – Pollen transferred to another flower by animal

Bee-pollinated – Don’t see red – See yellow, blue, green and UV light best so flowers that bees visit are these colours – UV markings on petals that only bees can see – UV colors and patterns in the petals dramatically announce the flower‘s nectar and pollen Birds see red and orange flowers well.

What colours do bees see? we see bees seeadd in UV redblackuv purple orange yellowgreen yellow/green* yellow uv purple greengreen blueblueuv violet violetblue blue uv blue purpleblue white bluegreen blue green black

Fertilization Refer to handout

Double Fertilization Occurs ONLY in angiosperm Pollen grain divides and form TWO sperm nuclei – One fuses with the egg to form a zygote – The second one (n) fuses with the 2 polar nuclei (n x 2) Hence, 3N endosperm

Seed plants and human welfare Just 6 crops – wheat, rice, maize (corn), potatoes, cassava (manioc), sweet potatoes – yield 80% of all the calories consumed by humans Even so, most of our food currently comes from angiosperms

Seed plants and human welfare It takes ~5 pounds of grain to produce 1 pound of grain-fed beef