291 



mon anil the rnosl i ample tely know n, and 1^ one in which, formerly, botanists the 



least suspected anomalies of organization to exist. They found calyx and corolla 

 and nectaries here with the same facility as they found them in a Ranunculus ; 

 and yet it may be doubted whether such organs exist in any one genus of 

 Grasses. 



Before I advert to the affinities of this tribe, it is indispensable that the real 

 nature of this organization should be understood. I shall, therefore, without 

 occupying myself with the views of Linmeus and his school, first cite Mr. Ro- 

 bert Brown's account of their structure, and then proceed to offer some observa- 

 tions upon the views that other botanists have taken of the subject. 



Mr. Brown's statement is this : 



" The natural or most common structure of Gramineae is to have their sexual 

 organs surrounded by two floral envelopes, each of which usually consists of 

 two distinct valves ; but both of these envelopes are, in many genera of the ol- 

 der, subject to various degrees of imperfection or even suppression of their parts. 

 The outer envelope, or gluma of Jussieu,in mostcases containing several flowers 

 with distinct and often distant insertions on a common receptacle, can only be 

 ■considered as analogous to the bractese or involucrum of other plants. The 

 tendency to suppression in this envelope appears to be greater in the exterior or 

 lower valve ; so that a glurna consisting of one valve may, in all cases, be 

 considered as deprived of its outer or inferior valve. In certain genera with a 

 simple spike, as Lolium and Lepturus, this is clearly proved by the structure 

 of the terminal flower or spicula, which retains the natural number of parts ; 

 and in other genera not admitting of this direct proof, the fact is established by 

 a seriesof species showing its gradual obliteration, asin those species of Panicum 

 which connect that genus with Paspalum. On the other hand, in the inner 

 envelope, or calyx of Jussieu, obliteration first takes place in the inner or upper 

 valve; but this valve having, instead of one central nerve, two nerves equidistant 

 from its axis, I consider it as composed of two confluent valves, analogous to what 

 takes place in the calyx and corolla of many irregular flowers of other classes ; 

 and this confluence may be regarded as the first step towards its obliteration, 

 which is complete in many species of Panicum, in Andropogon, Pappophorum, 

 Alopecurus, Trichodium, and several other genera. With respect to the na- 

 ture of this inner or proper envelope of Grasses, it may be observed, that the 

 view of its structure now given, in reducing its parts to the usual ternary divi- 

 sion of Monocotyledones, affords an additional argument for considering it as 

 the real perianthium. This argument, however, is not conclusive, for a similar 

 confluence takes place between the two inner lateral bractese of the greater 

 part of Irideae ; and with these, in the relative insertion of its valves, the proper 

 envelope of Grasses may be supposed much better to accord than with a ge- 

 nuine perianthium. If, therefore, this inner envelope of Grasses be regarded as 

 consisting merely of bracteae, the real perianthium of the order must be looked 

 for in those minute scales, which, in the greater part of its genera are found im- 

 mediately surrounding the sexual organs. These scales are, in most cases, 

 only two in number, and placed collaterally within the inferior valve of the pro- 

 per envelope. In their real insertion, however, they alternate with* the valves 

 of this envelope, as is obviously the case in Ehrharta and certain other genera ; 

 and their collateral approximation maybe considered as a tendency to that 

 confluence which uniformly exists in the parts composing the upper valve of 

 the proper envelope, and which takes place also between these two squama? 

 themselves, in some genera, as Glyceria and Melica. In certain other genera, 

 as Bambusa and Stipa, a third squamula exists, which is placed opposite to 

 the axis of the upper valve of the proper envelope, or, to speak in conformity 

 with the view already taken of the structure of this valve, opposite to the junc- 

 tion of its two component parts, With these squamae the stamina in triandrous 



