THE GRASSES 19 



fertilizing- dust ( pollen j and suspended by slender threads 

 (filaments). The flowers may have stamens alone (staminatc 

 flowers) or pistils (pistillate flowers) or both (perfect or 

 hermaphrodite flowers), or the floral glumes may be empty 

 by the atrophy of the parts, when the flowers are neutral. 

 When the flowers have but one kind of organs present they 

 are said to be unisexual. When the unisexual flowers of 

 both kinds are on the same plant the plant is monoecious: if 

 the flowers of the two sexes are on different plants the 

 species is dioecious. If both perfect and unisexual flowers 

 are on the same plant it is said to be polygamous. 



Inside the floret at the base are 1 to 3. usually 2, 

 thin transparent scales called lodicules which can only be seen 

 with a lens. The small stem to which the florets are attached 

 in the spikelets is called rachilla. The fruit is called a cary- 

 opsis or grain. 



The diagram shows a single culm with its attendant 

 sheaths, leaves, ligules and i-'anicle in the figure A. Figure 

 B. represents a spikelet having several flowers. Figure C. 

 shows a single floret from P. still farther magnified with its 

 parts numbered. Figure D rei)resents a single-flowered 

 spikelet dissected to show the parts which are numbered and 

 explained. 



It should be remembered that the keys are largely 

 artificial and that any slight difference which is easily seen 

 is usually taken to separate species or genera, because there 

 are so very many different and easily recognizable species 

 that it is almost impossible to separate by description. In- 

 significant characters are used in much the same way that one 

 would describe a man as having lost a particular finger or 

 having a special birthmark. It serves not to describe but to 

 distinguish him from all others but is of little importance 

 otherwise. 



