Chapter 13 Flowering Plants

Chapter 13 : Flowering plants Phylum Anthophyta (or Magnoliophyta) This is the only phylum of seed plants that is not included in gymnosperms. Anthophyta evolved recently ( 150 million years ago ). Fossils. There are roughly 350,000 species (much more than all the gymnosperms). Anthophyta have efficient vessels in the xylem to carry water (gymnosperms have tracheids instead of vessels). Flowering plants are typically insect pollinated. Flowers consist of : sepals ( protect the flower bud ) petals ( attract pollinators ). stamens ( anther, filament ) produce pollen. carpels or pistils ( stigma, style, ovary ) produce the egg. Anthophyta have double fertilization : one male gamete fertilizes the egg ( making an embryo ) and the other male gamete fuses with 2 polar nuclei (making a triploid endosperm ). The seed is released surrounded by the ovary, as a fruit. Plants have several defenses against herbivores: a) many plants produce toxic chemicals. b) plants may have mutualistic relationships with animals such as ants, which keep herbivores away.Ant/acacia mutualism c) plants may release chemicals to attract predators that feed on herbivores. Chemical defense. Most wild plants are flowering plants. Duval county plants. Anthophyta are vital as crops, including GM (genetically modified) plants. Classes of Anthophyta Monocotyledons Dicotyledons One cotyledon (seed leaf) Two cotyledons Parallel leaf veins Net-like veins in the leaf Scattered vascular bundles Vascular bundles in a ring No cambium May have cambium Flower parts in multiples of 3 Flower parts in 2, 4 or 5 Fibrous roots Tap roots eg wheat, grasses, palms eg rose, oak, tomato Pollination of Flowers Color Pollinator Example Yellow or blue Insects eg bees Vanilla White (opens at night) Bats Musa (banana) White( opens in day ) Beetles Magnolia Red Green Bird Wind Hibiscus Zea ( corn ) Seed dispersal There are three main types: 1. Wind - light seeds with hairs or wings eg Acer - tumbleweeds : the whole plant blows around eg Salsola Wind dispersal 2. Water - floating seeds eg Cocos ( coconut ) 3. Animals - hooks, barbs catch on fur eg Bidens. - ants collect seeds that have an elaiosome eg Acacia. - larger fruits have hard seeds that can survive through the animals digestive system eg Malus (apple). Seeds Hot pepper seeds are spread by birds, not mammals: Peppers Some cultivated plants, like bananas, produce fruit without seeds, which is called parthenocarpy. Seedless tomatoes and grapes are often sprayed with plant hormones to artificially produce parthenocarpy. Finally seedless watermelons are produced by crossing two varieties that have different numbers of chromsomes, so the offspring are sterile (just like a mule, produced by crossing a horse and donkey, is always sterile).