4 GENERAL CHARACTERISTICS [CH. 



whether in flower or not, forced itself on the attention, 

 and although a botanist naturally turns to a good Flora 

 when he has the grass in flower, as the best and quickest 

 way of ascertaining the species, it soon became evident 

 that much maj' be done by the study of the leaves and 

 vegetative parts of most grasses. Indeed some are recog- 

 nisable at a glance by certain characters well known to 

 continental observers: in the case of others the matter 

 is more difficult, and perhaps with a few it is impossible 

 to be certain of the species from such characters only. 



Nevertheless, while the best means for the deter- 

 mination of species are always in the floral characters so 

 well worked up in the Floras of Hooker, Bentham and 

 others, there is unquestionably much value in the 

 characters of the vegetative organs also, as the works 

 of Jessen, Lund, Stebler, Vesque and others abroad, and 

 Sinclair, Parnell, Sowerby and others in this country 

 attest. 



Almost the only plants confounded with true grasses 

 by the ordinary observer are the sedges and a few rushes. 

 Apart from the very different floral structures, there are 

 two or three easily discoverable marks for distinguishing 

 all our grasses from other plants (Fig. 1). The first is 

 their leaves are arranged in two rows, alternately, up the 

 stems ; and the second that their stems are circular or 

 flattened in section, or if of some other shape they are 

 never triangular and solid'^ (Figs. 6 and 7). Moreover the 

 leaves are always of some elongated shape, and without 



1 Some foreign grasses {Aiidropogon, Panieum, &o.) have solid stems, 

 and in Psamma and some others the lower parts may be solid. 



