49° The Ohio Naturalist. [Vol. XII, No. 5, 



A REVISED TAXONOMY OF THE GRASSES.^ 



John H. Schaffner. 



Ha\'ing had occasion to study the grass flora of Ohio in connec- 

 tion with the preparation of a forthcoming catalog of Ohio plants 

 and having paid considerable attention to the phyletic arrange- 

 ment of the flowering plants, it soon became evident to the writer 

 that the usual arrangement, as given in recent systematic works, 

 reverses the order of nature and the rational method of presenta- 

 tion. To begin the grass series with plants having such specialized 

 structures as one finds in Zea, Coix, and Tripsacum, is to intimate 

 that the grasses have been evolving from the specialized to the 

 unspecialized, from the unique to the nomial, from the particular 

 to the general. 



If one makes a general study of the spikelet and flower, the 

 order of progress is indicated in a remarkably clear manner by a 

 long series of degenerations and vestigial parts. The evidence 

 is incontrovertable to anyone ^^'ho can entertain any modern 

 views on the doctrine of evolution as applied to these plants. The 

 conclusion seems inevitable — the bamboos and arundinarias are 

 the most primitive grasses while gama-grass, Job's-tears, and 

 Indian corn are among the most extreme specializations to be 

 found not alone in the Graminaceae but even in the whole group of 

 flowering plants. 



In order to present the arrangement clearly to students of 

 systematic botany, a brief description of the teniiinology, with a 

 synopsis of the tribes usually recognized and a systematic list of 

 the local genera, is given below. 



TERMINOLOGY OF THE GRASS INFLORESCENCE 



The inflorescence of a grass is made up of compact flower- 

 bearing branchlets known as spikelets. In general, the spikelet 

 of a grass is of the same importance in identification as the flower 

 in most other groups. The spikelet usually has two bracts at the 

 base which are called the empty glumes. These may be disting- 

 uished as the outer and inner empty glumes. Each flower is also 

 normally inclosed in two bracts, called the flowering glumes. The 

 outer of these glumes is called the lemma the inner the palet. All 

 of these bracts can thus be called glumes collectively. Through 

 reduction of the spikelet and degeneration of the flower, part of 

 the glumes may be absent or vestigial, or extra glumes may 

 be present. Usually there are 2 (sometimes 3) minute bracts or 

 scales at the base of the flower, within the flowering glumes. These 



1 Contribution.s from the Botanical Laboratory of Ohio State 

 University, 67, 



