• 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