An incomplete flower is defined as a flower missing any of its parts in its natural form, i. e. petals, sepals, stamens or pistils.

A related term is "imperfect flower" indicating flowers that lack either stamens or pistils. Imperfect flowers that bear only pistils are called pistillate flowers (or female flowers) and those that bear only stamens are called staminate flowers (or male flowers).

Plants having separate imperfect male and female flowers on one plant are referred to as "monoecious". When the flowers are on different plants the species is referred to as "dioecious".

Courtesy of NYBG Plant Information Service