Review From Thursday What is one difference between an angiosperm and a gymnosperm? What organism did plants most likely evolve from? What is the name of the type of tissue that helps conduct water and other materials throughout a plant? What are xylem and phloem? Give an example of a seedless nonvascular plant.

Seed Plants

Gymnosperms – naked seeds Cones are the seed-bearing structures of gymnosperms Ex: conifers pollination is usually by the wind

Angiosperms – enclosed seeds Flowering plants Largest and most diverse groups of plants on earth Flowers are the seed-bearing structures of angiosperms Ex - Fruits

Angiosperms can be classified as monocots or dicots Based on: number of cotyledons (seed leaves) Arrangement of vascular bundles (xylem and phloem) Type of roots How veins are arranged in leaves Arrangement of floral parts

Diversity of Angiosperms Monocots Dicots Seeds Single cotyledon Two cotyledons Leaves Parallel veins Branched veins Flowers Floral parts often in multiples of 3 Floral parts often in multiples of 4 or 5 Xylem and Phloem scattered Arranged in a ring Roots Fibrous roots Taproot

Annuals, Biennials, Perennials Annuals: grow from seed to maturity, flower, produce seeds, and die all in the course of one growing season. Biennials complete their life cycle in 2 years Perennials – live through many years Marigolds = Annuals Parley = Biennial Palm tree = Perennial

Woody and Herbaceous Angiosperms Woody: Made primarily of thick cell walls that support the plant body Trees, shrubs, and vines Herbaceous: Smooth, non-woody plant stems Dandelions, petunias, and sunflowers

Structure of flowers Flowers are reproductive organs that are composed of four kinds of specialized leaves: Sepals Petals Carpels Stamens

Sepals and Petals: Outermost parts Sepals are the outermost part of a flower that protects a flower while it is developing Petals are found just inside the sepals, often brightly colored to attract insects and other pollinators to the flower

Stamens and Carpals: Reproductive Parts Stamens: Male part of the flower, produces pollen grains a.k.a “plant sperm” Filaments – holds anther up in air Anthers – produces pollen Carpals – female reproductive parts Stigma – sticky to catch pollen Style – long tube Ovaries – contain eggs that will develop into seeds when fertilized

Seed structure Embryo – young plant 3 basic parts Embryo – young plant Endosperm – supply of nutrients for the embryo Seed Coat – protects the embryo

Pollination Pollen lands on sticky stigma, pollen tube starts forming so pollen can travel to egg in ovule = sexual reproduction A fertilized eggs forms into an embryo inside of a seed In angiosperms, the ovary wall thickens and forms into a fruit around the seed

Seed Dispersal 3 Ways: Wind Water Animals Common in gymnosperms Seeds are lightweight Water Usually seeds can float, ex: coconuts Animals Most angiosperms Why is this advantageous? Why do flowers look pretty and smell good?

Seed Dormancy Once seeds are dispersed, they often enter a state of dormancy – when the embryo is alive but not growing Allows for long distance dispersal and ideal growth conditions Seeds will come out of dormancy and begin to grow when environmental factors like temperature and moisture improve