230 A TEXT-BOOK OF BOTANY 
sperms, called A/onocotyledons and Dicotyledons, are char- 
acterized by them, the former having the parts of the 
flower in threes, the latter in fives. This does not mean 
that. all flowers of these two divisions have one or the other 
number, but that these are the prevailing numbers in case 
there is a definite number at all. Not a few Dicotyledons 
have flowers with the parts in threes, and a still larger 
number have them in fours. 
137. Staminate and pistillate flowers.—In many cases 
stamens and pistils are not found together in the same 
flower. In such cases there are staminate flowers, that is, 
those without pistils; and pistillate flowers, that is, those 
without stamens. These two kinds of flowers may be 
borne upon the same plant, which is then said to be 
monecious (one household); or upon different plants, 
which are then said to be diwcious (two households). These 
terms are applied indifferently to the plants or to the 
flowers, either the plants or the flowers being spoken of as 
moncecious or dicecious. In a dicecious plant, therefore, 
Fig. 218.—Hypogynous flower of Potentilla (A), and epigynous flower of apple 
(B).—After ENGLER and PRANTL. 
one can speak of staminate and pistillate plants, one bear- 
ing fruit and seed and the other not. Many of our common 
trees, as willows and poplars, arc dicecious; and many more, 
as oaks, walnuts, and hickories, are moneecious. 
