Botany and Plant Science

The margin is having the tooth like that of a saw

they are present below the level of epidermis thus called sunken.

these structures are present in phyllocalde and are absent in phyllode

the lamina is in the shape of an arrow

Fertilization is the biological process where male and female gametes fuse to form a zygote. This is the correct term for the fusion of reproductive cells in sexual reproduction.

Pollination is the transfer of pollen grains from the anther (male part) to the stigma (female part) of a flower. This is the correct botanical term for this process, which is a prerequisite for fertilization in plants.

Self sterility is a physiological mechanism where pollen from the anther cannot germinate on the stigma of the same flower. This prevents self-pollination and promotes cross-pollination, increasing genetic diversity.

Cross pollination is the transfer of pollen grains from the anthers of one plant to the stigma of a flower on a different plant of the same species. This promotes genetic variation and is contrasted with self-pollination.

Pistillate flowers contain only female reproductive organs (pistil), which includes the stigma, style, and ovary. Gynoecium refers to the collective female parts, but pistillate specifically describes flowers with only these female structures. Perianth is the non-reproductive outer parts, and androecium refers to male structures.

Self-pollination occurs when pollen from an anther fertilizes the stigma of either the same flower (autogamy) or another flower on the same plant (geitonogamy). Cross pollination involves different plants, fertilization is the fusion of gametes, and pollination is the broader process.

Herkogamy is a structural mechanism where physical barriers (like unequal stamen and stigma positions or floral architecture) prevent self-pollination. Protogyny and protandry are temporal mechanisms (timing differences), while heterostyly involves different style lengths in different flowers.

The fusion of two polar nuclei (in the embryo sac) with one male gamete forms the triploid (3n) endosperm nucleus, which develops into nutritive endosperm tissue. The zygote forms from egg + male gamete, while tube and generative nuclei are pollen structures.

After fertilization, the zygote develops a cell wall and becomes the oospore, a resting stage that then develops into the embryo. The ovule develops into the seed, not the zygote itself. Calyx and corolla are floral whorls.

The oospore develops through mitotic divisions to form the embryo (the immature sporophyte). The ovule develops into the seed (containing the embryo), and the ovary develops into the fruit. Endosperm is the nutritive tissue.

Angiosperms exhibit double fertilization: one male gamete fuses with the egg to form the zygote, and another fuses with polar nuclei to form the endosperm nucleus. This unique process is characteristic of flowering plants.