Endosperm development is a characteristic feature of all families of angiosperms except for which of the following families?
Orchidaceae
Podostemaceae
Trapaceae
Onagraceae
Endosperm development is a characteristic feature of all families of angiosperms except for the family Orchidaceae. Endosperm is a tissue that develops within the seed and provides nutrition to the developing embryo. However, in Orchidaceae (orchid family), endosperm development does not occur.
Instead, orchids have a unique type of seed called a "dust seed" or "naked seed" where the embryo develops directly from the fertilized egg without the formation of an endosperm. This adaptation allows orchids to produce small and lightweight seeds that lack a bulky endosperm, enabling them to disperse more easily through wind or other means.
So, while endosperm development is a common feature in most angiosperm families, it is absent in the family Orchidaceae. Hence, the correct answer is option 1.