ANGIOSPERMS : • Called flowering plants and have seeds enclos | .
ANGIOSPERMS : • Called flowering plants and have seeds enclosed in fruits.
• Divided into two classes − Dicotyledons (have two cotyledons) and Mono-cotyledons (have one cotyledon).
• Smallest angiosperm : Wolfia
• Large tree : Eucalyptus
Stamen has filament and anther. Anthers bear pollen grains. Pollen grains have two male gametes.
• Pistil has stigma, style and ovary. Ovary has ovule in which female game-tophyte (embry sac) develops.
• Embryo sac has 7 cells and 8 nuclei. One egg cell, 2 synergids, 3 antipodals and two polar nuclei which fuse to form secondary nucleus.
• Pollen grain is carried by wind, water etc. reaches to stigma and produces pollen tube which enters embryo sac.
• Double fertilisation : One male gamete fuses with egg cell to form zygote which develops into embryo. Other male gamete fuses with secondary nucleus which forms triploid primary endosperm nucleus (PEN). PEN develops into endosperm which nourishes the developing embryo.
•Ovules develop into seeds and ovaries into fruits.
