THE PHYLOGRNY OF THE GRASSES * 



BY ERNST A. BESSEY. 



It is a truism that one often "cannot see the forest for trees." This 

 applies too often in systematic botany. The now-a-days often despised 

 but none tlie less indispensable specialist in the various genera and 

 families of plants frequently seems to lack the necessary perspective 

 which would enable him to group his species and genera to correspond 

 to some more general scheme of phylogeny. The modern systematist, to 

 be sure, believes in evolution and strives to arrange his species in diverg- 

 ing series in accordance with the probable evolutionary sequences in the 

 group. But without the perspective the group may be "stood on its 

 head," as it were, without interrupting the evolutionary continuity within 

 the group. Yet such a treatment interferes greatly with the linking 

 together of families, orders, and higher groups into an orderly system. 

 Sometimes an arrangement adopted before the advent of evolutionary 

 ideas is retained, long after all botanists have become evolutionists. 



Such then, has been the fate of the grasses (Family Poaceae). The 

 present division into twelve to fifteen tribes was, as it were, crystallized 

 by Bentham and Hooker in their invaluable work "Genera Plantarum," 

 a work too often neglected in favor of the perhaps more easily read 

 "Natuerliche Pflanzenfamilien" of Engler and Prantl. Hackel, the great 

 Austrian grass specialist, who worked over this family for the last men- 

 tioned work, followed in the main, the tribal divisions and arrangement 

 of Bentham and Hooker, with some improvements. It is essentially this 

 arrangement that the eminent American authority on grasses, A. S. 

 Hitchcock, follows in his treatment of grasses in the New Gray's Manual 

 and that Nash follows in Britton and Brown's Illustrated Flora. 



In the foregoing arrangements the first tribe is the Maydeae, followed 

 by the Andropogoneae, Paniceae, Oryzeae, Phalarideae, Agrostideacj 

 Aveneae, Chlorideae (not mentioning several smaller, mostly tropical 

 tribes) and winding up with the Festuceae, Hordeae and Bambuseae. It 

 is not at all impossible to erect a phylogenetic tree in which the Maydeae, 

 Andropogoneae and Paniceae shall be the trunk and basal branches, 

 with the Festuceae, Hordeae and Bambuseae as the expression of the 



19th Mich. Acad. Sci. Rept., 1917. 



*The reader is referred to the brief popular paper on this same subject by W. H. Lamb, 

 based, in its main features, like the present paper, on the unpublished work of Charles 

 E. Bessey. 



