Tag: what is a seed?

Dicotylodoneae is a group of angiosperms that are characterized by tap root system, vascular tissue present in columns, posses xylem vessels, leaves have reticulate venation, stem with open collateral vascular bundles arranged in a ring and seed are covered by fruits and show secondary growth.

Perisperm differs from endosperm in being a diploid tissue. Endosperm is a tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. These are typically triploid but can vary widely from diploid. Endosperm that is diploid, resulting from the fusion of a pollen nucleus with one, rather than two, maternal nuclei.They are both nutritive layers in a seed. Perisperm develops from the nucellus of the seed and the endosperm develops when the sperm cell fuses with two haploid polar nuclei (contained in the central cell) in the centre of the embryo sac (or ovule). The resulting cell is triploid (3n). This triploid cell divides through mitosis and forms the endosperm, a nutrient-rich tissue, inside the seed. 

Composite fruit is a type of fruit that develops from an inflorescence rather than from a single flower while custard apple fruit develops from a polycarpellary and apocarpous ovary. It forms from the pistils and receptacle of one flower. Custard apple is an example of aggregate fruit.

The coconut is also a drupe, but the mesocarp is fibrous or dry (termed a husk), so this type of fruit is classified as a simple dry fruit, fibrous drupe. Unlike other drupes, the coconut seed is unlikely to be dispersed by being swallowed by fauna, due to its large size. It can, however, float extremely long distances across oceans.

Cremocarp is the fruit of family Umbelliferae consisting of a pair of carpels pendent from a supporting axis. The fruits are nonfleshy schizocarp of two mericarps, each with a single seed; they separate at maturity and are dispersed by wind. Some fruit segments are covered in bristles and spread via external transport. The seeds have an oily endosperm and generally contain large quantities of fatty oils, with the fatty acid petroselinic acid occurring universally throughout the family while rarely being found outside of the Apiaceae.
Therefore, the correct answer is option A.

A true nut is a fruit composed of a hard shell and an edible seed. The shell does not open to release the seed (indehiscent), e.g., hazelnut, chestnuts, walnuts, almonds and pecans are drupes.

Seed coat is not thin in coconut. The fruit is an indehiscent fruit in which an outer fleshy part-exocarp or skin and mesocarp or flesh surrounds a shell of hardened endocarp with a seed inside. These fruits usually develop from a single carpel and mostly from flowers with superior ovaries. The definitive characteristic of a drupe is that the hard, lignified stone is derived from the ovary wall of the flower. The coconut is  a drupe, but the mesocarp is fibrous or dry, so this type of fruit is classified as a simple dry fruit, fibrous drupe. 
Therefore, the correct answer is option A.