DESCRIPTIONS OF THE TRIBES AND 

 GENERA. 



As an introduction to the series of illustrations 

 which appear in American Grasses, a description of 

 the several tribes and genera, into which the order 

 Gramineae is divided is here presented. The number 

 and sequence of the tribes adopted by Hackel has been 

 followed and with few exceptions the same is true of 

 the genera. It has been aptly stated that the secret 

 of success in the discrimination of grasses lies in being 

 thoroughly conversant with the tribal and generic 

 characters. The acquisition of this knowledge is not 

 difficult, and, when mastered, enables one to classify or 

 to refer to its proper tribe and genus any grass he 

 may meet — a power which adds greatry to the interest 

 connected with the study of all plants. It is hoped 

 that the matter here presented will at least assist the 

 student of grasses in becoming better acquainted with 

 the most important of all the orders in the vegetable 

 kingdom — the true grasses. 



GKRAMINEiE (GRASSES). 



Fibrous-rooted, annual or perennial, herbaceous; (rarely woody) 

 plants, with usually hollow, cylindrical (rarely flattened) , and 

 jointed stems (culms) whose internodes for more or less of their 

 length are enveloped by the sheath-like basal portion of the two- 

 ranked and usually linear, parallel-veined leaves; flowers without 

 any distinct perianth, hermaphrodite or rarely unisexual, solitary 

 or several together, in spikelets, which are arranged in panicles, 

 racemes, or spikes, and which consist of a shortened axis (the 

 rachilla) and two or more chaff -like, distichous, imbricated bracts 

 (glumes) , of which the first two, rarely one or none or more than 

 two, are empty (empty glumes) ; in the axil of each of the succeed- 

 ing bracts (excepting sometimes the uppermost) is borne a flower 



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