BIOL 3560 Lecture Notes - Flowering Plant, Eudicots, Gynoecium
Document Summary
Chapter 20- evolution of the angiosperms: angiosperm appeared in first fossil record as pollen about 135 mya, molecular evidence suggests 140 180 mya, world wide dominance by 90mya and continues to this day, largest groups of species is plants in the world by far. Angiosperm characters: flowers, ovules/seeds enclosed by a carpel, double fertilization leading to endosperm, a reduced, 3 nucleate microgametophyte, a reduced 8 nucleate, 70celled megaagametophyte (most frequent, stamens with two pairs of pollen sacs, sieve tube elements and companion cells in phloem. Commonly present: shrubby plant, lacks vessels in xylem, lacks distinct sepals and petals, unisexual, dioecious, gametophyte eight cells/nine nuclei, the nymphaeales, herbaceous, aquatic plants, high light, lack vessels or tracheid like vessels, four celled, four nucleate embryo sacks, the austrobaieyales, shrubby, understory (low light), four celled, four nucleate embryo sacs, floral organs are spirally arranged; progressive changes between organ types and numbers.
