Chapter 30 Plant Diversity 2 Reproductive adaptations of seed plants Heterospory and reduced gametes o All seed plants are heterosporous they make two types of spores Megaspore grows into the female gametophyte Microspore grows into the male gametophyte o These spores are never released from the sporophyte o Gametophytes are tiny retained and nourished by the larger sporophyte The gametophytes are microscopic Ovules female o They form because the megasporangium retains the megaspore The megaspore grown into the female gametophyte o The ovule includes 30 3 A protective tissue 2n from the sporophyte called integument Megasporangium Megaspore Pollen male o Formed because the microsporangium retains microspores Microspores grow into tiny male gametophytes that become pollen grains o Pollen grains travel through the air to reach the female parts Resistant due to sporopollenin coat This is a new stem in sex Pollination o Pollen grain then grown pollen tube toward egg with in the ovule Sperm are released within the pllen tube They have no flagella in conifers and angiosperms Fertilization occurs within the ovule No rain or dew needed Seeds o Develops from the fertilized ovule Includes the seed coat food supply and embryo o Enhances survival on land Efficient adaptive dispersal Animals Wind Float in water Underground germination is possible Stored food allows embryo growth without photosynthesis The seed may stay dormant until conditions are ok to germinate Gymnosperm The naked seed plants Ovules born exposed on sporophylls o Usually arranged in cones gynko plants are the exception o No flower no fruit no protected ovary Gymnosperm Evolution Progymnosperms tree like but no seeds heterosporous woody Age of the dinosuars warmer and dryer dominated by conifers End of the age of dinosuars diversifying of the angiosperms Phylum Ginkgophyta Extant species Ginko bilboa Herbal medicine Falgellated sperm Female sporophylls not cones fleshy seeds are not fruit Male sporophylls in strobili Phylum Cycadophyta Palm tree like form about 100 species Ex Zania species in FL sago palm Central male or female cones Flagellated sperm Phylum Gnetophyta 3 distinct genera about 70 species Sperm not motile Fmale and female cones Ex Ephedra in US deserts Phylum Coniferophyta Most diverse gymnosperms today o Cone bearers 30 6 Male pollen cone sperm not motile Female ovulate cones Dominate high altitudes and latitudes in the Northern hemisphere Most are evergreen with needle like leaves Ex Pine fir spruce larch hemlock cedar juniper juniper berries are fleshy cones cypress redwood sequoia pacific yew source of taxol a cancer drug fleshy cones with single seed Record breakers tallest organism oldest organism Bristlecone pine most massive Know the pine life cycle 30 6 Angiosperms Derived Characteristics Flower o Protects ovules within the ovary o Makes pollen transfer efficient by attraction animal pollinators Fruit o Enhances seed dispersal o Protects dormant seed dispersal adaptation Flowers 4 whorls of modified leaves Learn the parts and functions of flower in 30 7 Flowers can be incomplete missing parts o Unisex flowers only carpels or stamens o No petals if wind pollinated 30 13 Flowers may be clustered in an inflorescence Floral color and scent attract pollinators Nectar and pollen are rewards for animal pollinators o Coevolution of plants and pollinators Butterfly and moth depend completely on flowering plants o Sometimes pollinators are tricked with no reward Fruit Derived from the ovary tissue after fertilization may include other flower parts Fleshy fruits adapted to be eaten by animals 30 8 11 o Seeds are scattered or pass through the gut
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