OUTLINE OF STRUCTURAL BOTANY 23 
willows and poplars. If the “pussies” of the willows are exam- 
ined with a little care it will be seen that the soft gray fur of a 
catkin from one tree covers only staminate flowers while the less 
smooth catkin from another tree covers exclusively pistillate 
flowers. 
An excellent example of a plant having both staminate and 
pistillate flowers, each in separate groups is found in the common 
Maize or Indian Corn.t In this case the tall “ tassel ” terminates 
the stalk and spreads into many almost horizontal branches each 
bearing a great number of staminate flowers. Below, at the side of 
the stalk, is a husky envelope from which protrudes a bundle of 
long slender filaments constituting the “silk.” Each of these 
green filaments is the extended portion of a pistillate flower, or 
more exactly, of two such flowers for in this case two pistils unite 
as one. When these silky filaments have arrived at the proper 
stage for fertilization or pollination the wind wafts some of the 
pollen grains from the tassel of the plant or from a neighboring 
plant which falls upon the silky filaments and thus each fiber 
becomes pollinated and the conditions of growth of the individual 
seeds are supplied when each filament has been subjected to the 
action of the pollen. 
Examples of extremely simple flowers in which both stamens 
and pistils are found in the same group,? are found in some of 
the aquatic plants such as the Zanichella (Fig. 26) of the fresh 
ponds where one or two pistils are situated at the axil of a leaf 
between two stamens. This simple arrangement constitutes the 
entire flower and indeed all the elements necessary to the develop- 
ment of the seed. 
When the flower is thus destitute of any floral envelope, naked,? 
it is usually the case that the pollination is effected by the agency 
of the wind or by water. 
In the more conspicuous flowers that which gives them their 
character as blooms, the ornamental part, is the perianth. 
1Linnaeus called plants having groups of staminate flowers only on one plant and 
pistillate flowers only on another of the same species Dioeceous (living in two 
houses), but when such separate groups are found on the same plant he called the 
plant Monoeceous (one house). Jussieu, a later botanist, called plants having sta- 
mens in one flower and pistils in another Diclinous and those having the stamens 
and pistils grouped in the same flower Monoclinous. 
When diclinous and monoclinous flowers are found on the same plant the plant 
said to be Polygamous. Flowers having both stamens and pistils are Hermaphro- 
ite. 
2 Such flowers are, in the technical sense perfect, because they contain both the 
elements for the perfection of the seed. They are not, however, complete, because 
they do not have the appendages of the higher orders of flowers, the calyx and 
corolla. t 
8 Flowers without a calyx or a corolla are apetalous or, more technically achlamyde- 
ous, words which in the technical works on systematic botany are important and 
not unfrequently used. 
