Mostly, monocot seeds are endospermic seed, i.e., that have endosperm. The tissue that surrounds and provides nutrients to the embryo in the seeds of angiosperms is known as endosperm. The endosperm in certain seeds such as pea and bean is completely absorbed when matured, and the embryo is nourished by the fleshy food-storing cotyledons. Some endosperms as in castor serve to the store food. The endosperm is formed by the process of double fertilization. Two male gametes fuse with one female gamete wherein one male gamete fertilizes the egg to form a zygote, whereas the other fuses with two polar nuclei to form endosperm. Generally, the seeds of orchids lack a well-defined endosperm, i.e., orchid seeds are non-endospermic seeds.
