Glum ALES.] 



GRAM1NACE.E. 



107 



Fii?. LXXIV. 



the joints, covered with a coat of silex, sometimes solid. Leaves narrow and undivided, 

 alternate, with a split sheath, and a membranous expansion (ligula) at the junction of 

 stalk and blade. Flowers green in little spikes called locustse, arranged in a spiked, racemed 

 or panicled manner. Flowers usually , sometimes monoecious or polygamous ; consist- 

 ing of imbricated bracts, of which the most exterior are called glumes, the mterior imme- 

 diateh' enclosing the stamens palece, and the innermost at the base of the ovary scales. 

 Glumes usually 2, alternate ; sometimes smgle, most commonly unequal. Palete 2, alter- 

 nate ; the lower or exterior simple, the upper or interior composed of 2 united by their 

 contiguous margins, and usually with 2 keels, together forming a kind of dislocated calyx. 

 Scales 2 or 3, sometimes wanting ; if 2, collateral, alternate with the palece, and next 

 the lower of them ; either distmct or united. Stamens hypogynous, 1, 2, 3, 4, 6, or 

 more, 1 of which alternates with the 2 hypogynous scales, and is therefore next the 

 lower palese ; anthers versatile. Ovary simple ; styles 2 or 3, very rarely combined 

 into one ; stigmas feathery or hairy ; oAnile ascending by a broad base, anatropal. 

 Pericarp usually undistinguishable from the seed, membranous. Albumen farinaceous ; 

 embryo lying on one side of the albumen at the base, lenticular, with a broad cotyledon 

 and a developed plumula ; and occasionally, but very rarely, with a second cotyledon 



on the outside of the plumula, and alter- 

 nate with the usual cotyledon. 



This most important Order offers 



great smgularities in its organisation, 



although it is one in which, formerly, 



botanists the least suspected anomalies 



to exist. They found calyx and corolla 



and nectaries here with the same facility 



as they found them in a Ranunculus ; 



and yet such organs exist in no one 



genus of Grasses. Their so-called 



flowers consist of green scales, not 



placed in whorls, but arranged one 



above the other, and are midoubtedly 



constiTActed of bracts alone. Not a trace 



is discoverable among them of calyx or 



corolla, properly so called, unless certain scales usually present, next 



the ovary, are to be so considered. Brown's accomit of theu' con- 

 struction is still the best that has been pubhshed. He says, — 



" The natm'al or most common structm'e of Graminese is to have then* sexual organs 

 surrounded by the floral envelopes, each of which usually consist of two distinct valves ; 

 but both of these envelopes are, in many genera of the order, subject to various degrees 

 of imperfection or even suppression of their parts. The outer envelope, or gluma of 

 Jussieu, in most cases containing several flowers with distinct and often distant mser- 

 tions on a common receptacle, can only be considered as analogous to the bractete 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 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 Leptunis, this is clearly proved by the structure of 

 the terminal flower or spicula, which retains the natm-al number of parts ; and in other 

 genera not admittmg of this direct proof, the fact is established by a series of species 

 showing its gradual obliteration, as in those species of Fanicum wliich connect that 

 genus \\-ith Paspalum. On the other hand, in the mner envelope, or calyx of Jussieu, 

 obliteration first takes place in the inner or upper valve ; but this valve havmg, 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, 

 Pappophorura, 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, m reducing its parts to the usual ternary division of Monocoty- 

 ledons, 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 bracteoe of the gi'eater 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, therefoi'e, this inner envelope of Grasses 



Fig. LXXIV.— 1. Section of ovary of Penicillaria spicata ; 2. section of grain of rice, showing the 

 lateral embryo. 



Fig. LXXV.— Section of an Oat ; o ovary, ( testa, a albumen, r radicle, g plumule, e cotyledon. 



LXXV 



