Presentation on theme: "Flowers Extraordinary diversity of color, size, form"— Presentation transcript:
1Flowers Extraordinary diversity of color, size, form Universal in objective – sexual reproduction for a rooted, stationary land plant!88% of all known plant species are flowering plants (260,000)
2Flowers: A Marvelous Innovation Flowering plants first appeared around 140 million years ago (Upper Jurassic).At that time the dominant forms of plant life were gymnosperms, cycads (at left), and ferns.Oldest flower fossil is 125 million years old.Slide text from:
3Flowers dominate (except…) Success of the flower as a repro. strategy makes it the dominant plant of the warmer latsIn far north or high altitudes, we see gymnosperms (like fir, spruce) remain
32Butterflies are great learners Butterflies, whose color vision detects more wavelengths than either humans' or bees', can also associate colors with rewards. In one of the more dramatic experiments, cabbage butterflies learned a color with beelike speed -- after just one experience with a reward. Given a choice of two colors, the butterflies picked the rewarding hue 82 percent of the time, reported Alcinda C. Lewis of Boulder, Colo., and a colleague in Insect-Plant Interactions (CRC Press, Boca Raton, Fla., 1990). Pipevine swallowtails learned a preference for yellow or magenta within 10 visits to treat-laden flowers, reported Weiss in the May 1997 Animal Behaviour.The butterflies could also keep two learned colors in mind for different purposes, Weiss says. She and Daniel R. Papaj of the University of Arizona have trained female pipevines to associate one color with sources of nectar and another with suitable spots for laying eggs.
37Isabel Friedman, Apis mellifera on Asteraceae, Morris Arboretum October 13, 2007
38Bees are important pollinators Bees’ bodies well adapted to receive, transfer pollenBees’ vision includes UV spectral regions, but bees do not distinguish red as a visible colorRed-colored flowers are often bird-pollinated and not adapted for bees(poinsettia, hibiscus, red-flowered sages)
40Colony Collapse Disorder? Researchers are concerned that trucking colonies around the country to pollinate crops, where they intermingle with other bees from all over, helps spread viruses and mites among colonies. Additionally, such continuous movement and re-settlement is considered by some a strain and disruption for the entire hive, possibly rendering it less resistant to all sorts of systemic disorder. One major US beekeeper reports moving his hives from Idaho to California in January, then to apple orchards in Washington in March, to North Dakota two months later, and then back to Idaho by November - a journey of several thousands of miles. Others move from Florida to New Hampshire or to Texas; nearly all visit California for the almond bloom in January. Keepers in Europe and Asia are generally far less mobile, with bee populations moving and mingling within a smaller geographic extent (although some keepers do move longer distances, it is much less common). This wider spread and intermingling in the US has resulted in far greater losses from Varroa mite infections in recent years.
47Figs! Reproductive captivity Figs are one of many fruits that aren’t really fruits (also true of the strawberry, the apple and pear (!) the durian and several others…)Fig wasps live and reproduce inside the “syconium” – a fig’s inflorescenceRay’s Figs of Israel
48Fig pollinationThe puzzle of the figWayne’s word on figs
49Fertilization follows pollination Pollination involves only the transfer of species-appropriate pollen to the receptive stigma of a flowerFertilization requires the union of pollemn sperm nucleus with an ovule’s egg cell and creation of a new diploid (2n) embryo
50Female sex cell is accompanied by accessory cells Meiosis in the megasporangium of ovary (megasporocyte) creates eight (8) haploid cells – one of these eight is the egg cell, two nearby are called synergids.Two other important nucleiare the polar bodies
51Male pollen must germinate and divide Pollen grains on stigma actually germinate and grow a pollen tube to provide passage through style to ovary.
59WHY have double fertilization? ♂Competing hypothesesReview consequences of double fertilizationShown at right, male and female gamete nuclei fusing to form embryo (top) and the 3 cells of 2nd fertilization fusing to form triploid cell to form endosperm(bottom)♀♂♀