VARIATIONS IN STRUCTURE 



281 



Flowers which have only stamens or only pistils are 

 called diclinous; those which have both stamens and 

 pistils are called monoclinous. 1 The flowers with which you 

 are most familiar are monoclinous. Diclinous flowers with 

 stamens are called 

 staminate ; those 

 with pistils are 

 called pistillate. 

 Not all diclinous 

 flowers lack a peri- 

 anth ; there are 

 many which have 

 both sepals and 

 petals. 



Diclinous flowers 

 are more primitive 

 than monoclinous 

 ones; that is, 

 flowers which pos- 

 sessed only stamens 

 or only pistils are 

 believed to have 

 preceded those pos- 

 sessing both sta- 

 mens and pistils. 

 The flowers of 

 nearly all gymno- 

 sperms are dicli- 



FiG. 101. — A group of cat-tails, showing the dense 

 spikes of very simple flowers. The upper, woolly 

 part of the spike is composed of pollen-producing 

 (staminate) flowers which die when the cat-tail is 

 ripe. The lower, dark part is composed of seed- 

 producing (pistillate) flowers. These flowers are 

 wind-pollinated and the pistillate ones ripen be- 

 fore the staminate ones of the same plant. 



' Diclinous flowers are also called unisexual or imperfect, and monoclinous 

 ones bisexual or perfect. These terms are objectionable. Flowers are not, 

 strictly speaking, sexual ; and diclinous flowers, while more simple, are not 

 less perfect than are monoclinous ones. 



