Chapter 30 Plant Diversity 2Reproductive adaptations of seed plants- Heterospory and reduced gameteso All seed plants are heterosporous –they make two types of spores Megaspore grows into the female gametophyte Microspore grows into the male gametophyteo These spores are never released from the sporophyteo 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 gametophyteo 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 grainso Pollen grains travel through the air to reach the female parts Resistant due to sporopollenin coat This is a new stem in sex-Pollinationo 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- Seedso Develops from the fertilized ovule Includes the seed coat, food supply and embryoo 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 germinateGymnospermThe “naked seed” plants- Ovules born “exposed” on sporophyllso Usually arranged in cones- gynko plants are the exceptiono No flower, no fruit, no protected ovaryGymnosperm 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 angiospermsPhylum Ginkgophyta- Extant species= Ginko bilboa- Herbal medicine- Falgellated sperm- Female sporophylls, not cones, fleshy seeds are not fruit- Male sporophylls in strobiliPhylum Cycadophyta- Palm tree-like form= about 100 species- Ex: Zania; species in FL sago palm- Central male or female cones- Flagellated spermPhylum Gnetophyta- 3 distinct genera= about 70 species- Sperm not motile- Fmale and female cones- Ex: Ephedra in US desertsPhylum Coniferophyta- Most diverse gymnosperms todayo 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)AngiospermsDerived Characteristics- Flowero Protects ovules within the ovaryo Makes pollen transfer efficient by attraction animal pollinators- Fruito Enhances seed dispersalo 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 stamenso 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 pollinatorso Coevolution of plants and pollinators Butterfly and moth depend completely on flowering plantso Sometimes pollinators are tricked with no rewardFruit- 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
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