Why do some asparagus plants have red berries, and some don't?
Asparagus is unusual among our garden plants in its flowering habit. While nearly all of our vegetables bear both stamens and pistils (containing pollen cells and egg cells, respectively) on the same plant or in the same flower, asparagus has two kinds of plants. About half bear only staminate (male) flowers; the others bear only pistillate (female) flowers from which the little red seed-bearing fruits develop. Both male and female plants must be grown near each other if seeds are to be obtained. All-male hybrid varieties don't produce berries.