III. Angiosperms - flowering plants, dominate most regions 250,000 species vs. 700 conifer species Supply nearly all our food and fiber for textiles, some lumber Refined vascular tissue - water transport more efficient Evolution of flower = responsible for unparalleled success Flowers - display male and female parts Insects and animals transfer pollen from male part of one flower, to female part of another flower. Advantage? (vs. wind)________ Flower = short stem w. modified leaves: sepals, petals, stamens, carpels.

Label flower to left w. all flower terms below: Sepals - green, enclose flower before it opens Petals - attract insects & other pollinators Stamen - filament (stalk) bearing a sac called anther. Anther is male organ in which pollen grains develop. Carpel = sticky tip called stigma, which traps pollen, the style (stalk) and the ovary, a chamber containing one or more ovules. Egg develops here.

Angiosperm life cycle is above: Sporophyte is the familiar plant; female gametophyte is w/I the ovule, & male gametophyte is the pollen. Pollen lands on stigma, tube goes down to ovule, deposits 2 sperm nuclei w/I female gametophyte = Double fertilization. One sperm cell fertilizes egg making zygote, developing into embryo. Second sperm cell fertilizes another female gametophyte cell which develops into a nutrient-storing tissue called endosperm.

Angiosperms cont: Embryo then has food w/I ovule Ovule develops into a seed Seed is enclosed W/I ovary = not naked. Fruit = ripened ovary of flower Fruit protects and helps disperse seeds Animals help disperse seeds too! All fruit and vegetable crops are angiosperms We will re-visit flowers and fruits in Ch.28 & in labs. Issues:Tropical rain forests are being destroyed for agricultural Coniferous forests are being destroyed for lumber and paper. Can you help??? End of Ch. 16