Seed Plants Botany - Ch 5
Seed Plants • Recall that seedless plants were either nonvascular or vascular… either way they did NOT produce seeds • Seeds can be found everywhere…acorns, dandelion seeds, kernels of corn, even peanuts! • Seeds are very common and often overlooked. • Seed plants are also vascular plants and are divided into 2 groups • Gymnosperms – bear their seeds on the surface of a cone (pine trees = pine cones) • Angiosperms – produce fruit or flower that protects the seeds (wildflowers or apple tree)
Seed Plants • Seed plants are not like mosses & ferns they do NOT need water for reproduction • As a result they can live just about anywhere. • Adaptations that allow seeds to reproduce without water include: flowers or cones, pollination, and embryo protection in seeds
Cones and Flowers • The gametes (called gametophytes in plants) are the sex cells that grow and mature in cones or in flowers • Cones are found in gymnosperms • Flowers are found in angiosperms
Pollen • In seed plants the entire male gamete is contained in a pollen grain. • This pollen grain must be carried to the female gamete by wind, insects, birds, and sometimes even bats. • The transfer of pollen to the female is called pollination
Seeds • A seed is an embryo (fetus) of a plant that is encased in a protective covering and surrounded by a food supply that provides nutrients as the embryo grows • A seed coat surrounds the embryo and keeps it from drying out • Seeds may have special tissues or structures that aid in their dispersal. Some are textured so they stick to fur or feathers of animals. Some seeds are eaten and dispersed after digestion • The embryo can stay in the seed for weeks, months, or even years
Gymnosperms • Gymnosperms include four groups: • Gnetophytes • Cycads • Ginkgoes • Conifers • These plants all reproduce with seeds that are exposed on cones • Gymnosperms means “naked seed”
Gnetophytes • There are about 70 gnetophyte (nee-toh-fy-tuh) species • They are found in mostly desert and tropical forest habitats
Cycads • There are about 300 species of Cycads (si-kad) • They are beautiful palmlike plants that reproduce with large cones • They are found in tropical places such as Mexico, Florida, Asia, Africa, and even Australia • They typically grow very slowly and live very long • They are sometimes confused with and mistaken for palms or ferns, but are only distantly related
Ginkgoes • Ginkgoes (ging-kohs) have only one species today • It is one of the oldest seed plant species today • Ginkgoes are often planted in city settings in the US where their toughness and resistance to air pollution make them popular shade trees
Conifers • Conifers are the most common gymnosperms with more than 600 species including pines, spruces, firs, cedars, and redwoods • The dominant plants over huge areas of land • They are more resistant to freezing and are found in all habitats
Conifers • Thrive in a wide variety of habitats such as mountains, sandy soil, cool areas, dry places, warm habitats • Their leaves are long and thin which reduces the surface area and are also covered by a waxy layer that limits the amount of water that can be lost by evaporation • Most conifers are evergreen meaning they retain their leaves all year. Needles can stay on a tree for 2-14 yrs & they are gradually replaced so that the tree is never bare
Flowering Plants • Flowering plants are called angiosperms • Flowering plants have quickly became the dominate type of plant life on Earth. The vast majority of living plant species reproduce with flowers • Angiosperms have reproductive organs called flowers, which attract animals that transport pollen from flower to flower making pollination more efficient than gymnosperms • Flowers contain ovaries that surround and protect seeds. After pollination the ovary develops into a fruit which protects the seed.
Flowering Plants • The fruit is a thick wall of tissue surrounding the seed. When the fruit is eaten by animals seeds can be dispersed many miles away from where they originated
Monocots & Dicots • The seed leaves of a plant embryo is called a cotyledon • Angiosperms can be monocotyledons (MONOCOTS) or dicotyledons (DICOTS) • Monocots - have 1 part to the seed; parallel veins; flowers have petals in multiples of 3; the veins are scattered throughout the stem; and they have fibrous roots; corn, wheat, lilies • Dicots – have 2 parts to the seed; branched veins; flower petals in multiples of 4 or 5; veins are arranged in a ring around the stem; and has 1 main taproot; clover, tomatoes, oaks, daisies; roses
Woody & Herbaceous • Woody and herbaceous plants: grouped according to their stems. • Woody plants are made primarily of cells with thick cell walls. This includes trees, shrubs, vines (grape and ivy), blueberries, and roses. • Herbaceous plants have stems that are smooth and nonwoody such as dandelions, sunflowers, and petunias
Annuals, Biennials, & Perennials • Annuals – grow, flower, produce seeds & die all in one growing season (ex: marigolds, pansies, wheat, cucumbers)
Annuals, Biennials, & Perennials • Biennials – complete life cycle in 2 growing seasons. The 1st year they grow roots, stems, and some leaves – 2nd year they grow flowers & seeds (ex: parsley & celery)
Annuals, Biennials, & Perennials • Perennials – live through many years; most have woody stems such as palm trees, maple trees, honey suckle. Herbaceous plants such as grass & asparagus that die in the winter but come back in the spring
Review Questions • Where can seeds be found? • What are the 2 types of seed plants? • How are seed plants different from mosses & ferns? • What are some adaptations seed plants have that allow them to reproduce? • What is a gamete? • What is pollen? • When pollen is transferred what is that called? • What is a seed? • How long can an embryo stay in a seed? • What do gymnosperms carry their seeds on?
What are the 4 types of gymnosperms? • Where do you find gnetophytes? • What do cycads look like? • How many different types of ginkgoes are there today? Why are they often planted? • What is a conifer? And where do you find them? • What is special about conifer leaves? • Where do you find seeds in a flowering plant? • What is another name for a flowering plant? • What is the fruit of a flowering plant? • What is a monocot?
How many flower petals does it have? What do the roots look like? • Examples of monocots? • What is a dicot? • How many flower petals does it have? What do the roots look like? • Examples of dicots? • How can you tell of a plant is a woody plant or an herbaceous plant?
Give an example of woody plants? Of herbaceous plants? • What is an annual? & Give an example • What is a biennial? & Give an example • What is a perennial? & Give an example