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organisation than any other among flowering plants, and is perhaps that of 

 which the organisation is to this day least understood, although it is among 

 the most common and the most completely known, and is one in which, 

 formerly, botanists the least suspected anomalies of organisation 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 organisation should be understood. I shall therefore, 

 without occupying myself with the views of Linnaeus and his school, first cite 

 Mr. Robert Brown's account of their structure, and then proceed to offer 

 some observations upon the views that other botanists have taken .of the 

 subject. 



Mr. Brown's statement is this : — 



" The natural or most common structure of Graminece 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 order, subject to various degrees of imperfection or even sup- 

 pression of their parts. The outer envelope, or gluma of Jussieu, in most 

 cases 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 gluma consist- 

 ing 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 Lep- 

 turus, 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 series of species shewing its 

 gradual obliteration, as in those species of Panicum which connect that genus 

 with Paspalum. On the other hand, in the inner envelope, or calyx of Jus- 

 sieu, 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, Pappopho- 

 rum, Alopecurus, Trichodium, and several other genera. With respect to 

 the nature 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 division of Monocotyledones, affords an additional argument for con- 

 sidering it as the real perianthium. This argument, however, is not conclu- 

 sive, for a similar confluence takes place between the two inner lateral bracteae 

 of the greater part of Iridese ; 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 genuine perianthium. If, therefore, this inner envelope 

 of Grasses be regarded as consisting merely of bracteee, the real perianthium 

 of the order must be looked for in those minute scales, which, in the greater 

 part of its genera are found immediately surrounding the sexual organs. 

 These scales are, in most cases, only two in number, and placed collaterally 

 within the inferior valve of the proper 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 approxima- 

 tion may be 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 squamae themselves, in some 



