4o8 THE GRAMINALES 



epidermal cells are very much thickened, stomata often sunken 

 in narrow furrows and practically all species have the power of 

 rolling up the leaves in dry seasons and thus reducing the leaf 

 surface and lessening transpiration. 



The flowers are exceptionally alike in structure and show about 

 the same state of floral development. While resembling those 

 of Typha in some particulars, they present several features 

 that indicate a decided advance over the previous group. Fig. 

 283 illustrates the common types of inflorescence found among 

 the grasses. The flowers are arranged on elongated branches, 

 but instead of a large bract ensheathing the inflorescence (see 

 Typha), each flower is inclosed by one or more small bracts 

 so arranged as to form a spike-like structure of overlapping 

 bracts (Fig. 283, 2). The two kinds of sporophylls may be 

 arranged in separate spikes or on different parts of the same 

 spike, or, as in many grasses, the stamens and pistils are developed 

 in the same flower. One or more of the lower bracts of a spike 

 are usually without flowers and above them are one to several 

 flowers enclosed by secondary bracts (Fig. 283, 4). Removing 

 the secondary bracts, the flower proper is seen (Fig. 284, 3^, 

 2,B). This consists in many of the grasses of three stamens 

 and one pistil and usually two small scale-like organs, the lodi- 

 cules, which assist by their expansion in forcing open the pro- 

 tecting bracts at the time of flowering. The stamen consists 

 of a long filament attached to the middle of the anther so that 

 the latter organ can swing at the end of the filament, an arrange- 

 ment known as the versatile anther. The stigma is often 

 brightly colored and of a delicate feathery character, indicating 

 that the plants are wind pollinated. The ovary contains a 

 single ovule. The manner of flowering of the numerous genera 

 of this order varies. In many cases the stigmas are first ex- 

 truded from the bracts and can therefore be crossed only with 

 the microspores from some earlier flowering plant. In other 

 instances, stigmas and anthers are extended together and in 

 some genera no injury results from the transfer of the micro- 

 spores to the stigmas of the same flower. It is worth any one's 

 time to note the time of flowering, the region on the spike where 



