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Flowering Plants.Pdf à food or water storage Flowering Plants à protection [Angiosperms] à asexual reproduction dominant plants in world today much more so than in any other plant group à90% of all living plant species A. Extra Support 235,000 known species prop roots & buttress roots roots that help support plant flowering plants were the last of the 4 main groups to appear in the fossil record eg prop roots: corn, sorghum, red mangrove, banyon tree 1st appeared ~130 MY ago eg. buttress roots: tropical figs à quickly spread and diversified vining stems have dominated the landscape for the last 100 Million weak stems - use other plants or objects for support years but can grow rapidly Characteristics of Flowering Plants: à don’t need to expend lots of energy on strength 1. highly adaptable vegetative organs may grow away from sunlight rather than toward it vegetative Organs of flowering plants generally à more likely to encounter a tree to grow on perform the typical functions as described some vines are twiners earlier stems grow spirally for support but in many cases they are often modified to others have other modifications to attach to support enhance certain properties in the plant: vines are most numerous in tropical forests à extra support à gas exchange eg. lianas à food gathering Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 1 Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 2 = woody vines with adhesive suckers produced by plants growing in swamps or connect tops of trees waterlogged soils provide walkways for animals have well developed system of internal air spaces that take oxygen to interior of root system adhesive roots eg. black mangrove, white mangrove, bald vines often produce special adventitious roots from cypress above ground stem with adhesive pads that stick to bark aquatic leaves tendrils floating leaves of many aquatic plants: some tendrils are modified leaves rather than stems àhave stomata on upper surface àsometimes hard to tell the difference) that àlong petioles to allow blade to float grasp and hold onto other structures àpetioles and submerged parts of plant have tendril may be whole leaf or only part of the leaf internal system of air ducts to take O to 2 underwater roots and stems eg. peas C. Food Gathering aerial roots on epiphytes à plants that grow on other plants window leaves (=fenestraria) eg. ball moss, spanish moss, bromeliads, orchids transparent windows on the tips of succulent leaves allow light to penetrate into the leaf for improved their roots are for anchoring only, not to absorb photosynthesis water or nutrients parasitic roots (=haustoria) B. Gas Exchange all parasitic plants are flowering plants (dicots only, not monocots) pneumatophores some parasitic plants use roots to penetrate host aerial “breathing” roots and absorb nutrients act like siphon to get oxygen to root cells eg. mistletoe, dodder, broomrapes, pinedrops Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 3 Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 4 insectivorous leaves storage leaves for catching bugs à extra nitrogen eg white potatoes, elephant ears some able to close quickly, some hold water, some the “eyes” of a potato are axillary buds produce sticky secretions bulbs & heads eg. venus fly trap, pitcher plants, sundews in both the stem is almost nonexistent D. Food & Water Storage à very short internodes succulent stems bulbs are surrounded by fleshy nonphotosynthetic, storage leaves used to store water usually partly underground eg. cacti, euphorbs covered by paper-like scales (=modified leaves) succulent leaves frequenty form smaller “daughter bulbs” some leaves (rather than stem) are adapted for storing water eg. lilies, onions, garlic, tulips, etc thick, fleshy leaves head has whorled leaves surrounding very short stem eg. jade plant, aloe vera some outer leaves are green and photosynthetic no paper-like scales tuberous roots & Storage taproots often biennials in 1st yr before “bolting” portions of some roots are enlarged for food storage eg. sweet potatoes, rhizomes rhizomes are underground stems tuberous stems in some plants they are enlarged to store food some rhizomes produce greatly thickened ends eg. irises = fleshy underground stems enlarged for food Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 5 Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 6 E. Protection horizontal above ground stems that grow along surface of ground spines have long internodes stems or leaves modified for protection against buds develop along stolon giving rise to new plants herbivores eg strawberry, bermuda grass, airplane plants some spines arising from the axils of leaves are modified stems = thorns rhizomes eg. large thorns of locust and mesquite trees horizontal underground stems most spines are modified leaves resemble roots but have nodes, buds etc, spines can be formed from whole leaf each piece can become a separate new plant eg. cacti eg irises, bamboo, ginger, many grasses, etc or just portion of leaf; 2. complex symbioses with fungi, bacteria and eg. holly, young live oak leaves animals enhance survival and efficiency prickles eg. fungi à mycorrhizae some stems produce surface prickles but they are not eg. bacteria à root nodules an integral part of the stem eg. ants in tropics they are outgrowths of the epidermis or ground tissue just beneath epidermis [more later] à they break off easily 3. much more efficient transport tissues eg roses structure of both xylem and phloem are more efficient than in gymnosperms F. Asexual Reproduction 4. no asexual reproductive organs or spores produced runners (=stolons) 5. sexual reproductive organ is the flower Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 7 Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 8 most (not all) flowers have both male and female mostly hermaphrodite parts à with male and female parts = most flowering plants are hermaphrodites some are dioecious with separate male or female a typical flower has 4 main parts: flowers a. sepals b. petals great diversity in flower structure c. stamens (male) = filament + anther àgreatly enhances reproductive success d. pistils (female) = stigma + style + ovary 6. seeds protected within a fruit a. sepals lowermost whorl produce resistant seed as in conifers leaflike but better protection inside fruit covers and protects flower bud gymnosperm cones produced ‘naked seeds’ all sepals together = calyx angiosperms surround seed with fruit b. petals also offers much greater variety of dispersal whorl just above (inside) sepals Flower Structure great variation in size, shape and color in flowering plants, sexual reproduction occurs in flowers sometimes fused to form tube all petals together = corolla are temporary structures c. stamens are extremely variable in size and shape just inside petals eg. Rafflesia flower is up to 3 ft across Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 9 Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 10 consist of filament and anthers b. or male and female flowers on the same plant à monoecious (hermaphrodite) anther = sac like structure that produces pollen eg. sedges, maize, oaks, hickories grains and a few of these can apparently switch their sex c. pistil à transsexuals; males produce female flowers and females producing male flowers female reproductive organs a flower with all four different parts = complete flower sometimes there are many pistils lacking one or more = incomplete flower each pistil consists of: some of these variations are due to the way flowers are pollinated stigma àon which pollen lands pollen grains must travel from anther of one flower to style àneck like structure stigma of another ovary àsac like, contains one or more self pollination à pollen travels to stigma of same flower ovules only a few flowers are self pollinating cross pollination à pollen travels to stigma of different plant each ovule contains an egg the flower evolved to facilitate fertilization of the many variations in flower structure egg in some species the flowers are unisexual in most conifers, pollen is carried by wind to female cone a relatively random process à separate male and female flowers a large part of the success of flowering plants is due to esp in wind pollinated plants, esp trees and shrubs the variety of pollenation a. sometimes on different plants à dioecious à provides much better mixing of genes eg. willows, poplars Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 11 Plants:Plant Diversity-Flowering Plants; Ziser Lecture Notes, 2015.2 12 large amounts of pollen produced eg. oak, willow, grasses; including some of our most flowering plants have coevolved with many kinds of important crops – wheat, corn and rice animals through most of their history 2. insect pollinators the color, smell and nectar of most flowers is to petals colorful and large attract the appropriate pollenator often with nectaries this close relationship between plants and pollinators has resulted in coevolution much less pollen produced insects can be attracted by showy flowers, smell &/or nectar à mutual adaptations for mutual benefits a. bee & wasp pollinated plant: petals, scent, nectaries pollenate more flowers than any other group animal: special body parts and behaviors 20,000 different species of bees are important pollinators We like to think of animals as the most ‘evolved’ lifeforms
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