154 A TEXT-BOOK OF GRASSES 



194. The grass family and its subdivisions. — The 



genera of plants are grouped into families, and these into 

 orders and higher divisions of the vegetable kingdom. 

 The grass family is called Poacese or Graminese, and this 

 with the Cyperaceae (sedges) constitute the order Poales 

 or Glumiflorae. 



The term Poales is used for the order in the "North American 

 Flora," the termination -ales being uniformly added to a generic 

 stem to form the names of orders. Glumiflorse is used by Engler 

 and Prantl in their "Pflanzenfamilien." Glumaceae is used by Ben- 

 tham and Hooker ("Genera Plantanim") as the name of the series 

 that includes Eriocauleae, Centrolepidese, Restiaceae, Cyperaceae and 

 Gramineae. The classification here adopted is in the main that of 

 Bentham and Hooker ("General Plantarum") and of Hackel 

 ("Pflanzenfamihen"). The latter author will be followed in the 

 enumeration of the tribes. Although Hackel's classification is in 

 some respects artificial, it is on the whole the most natural arrange- 

 ment yet proposed. 



The family Poacese has been divided for convenience 

 into 2 series and 13 tribes. 



195. The 2 series of tribes. — Modem agrostologists 

 usually divide the genera of grasses into 2 series. The 

 first series Panicoideae (or Panicacese), the more highly 

 developed or modified, is characterized as follows: Spike- 

 lets with 1 terminal perfect floret and often a staminate 

 or neutral floret below; an articulation below the spikelet, 

 sometimes in the pedicel, sometimes in the rachis, some- 

 times at the base of a cluster of spikelets, the spikelets 

 falling away at maturity singly or in groups, or with 

 portions of the rachis; spikelets usually more or less 

 dorsally compressed, rarely laterally compressed. The 

 second series, Poseoidese, is characterized as follows: 

 Spikelets with 1 to many florets, the imperfect ones 

 when present usually being above; rachilla often artic- 



