292 



Grasses alternate, and they are consequently opposite to the parts of the proper 

 envelope ; that is, one stamen is opposed to the axis of its lower or outer valve, 

 and the two others are placed opposite to the two nerves of the upper valve. 

 Hence, if the inner envelope be considered as consisting of bractea?, and the hy- 

 pogynous squamae as forming the perianthium, it. seems to follow, from the re- 

 lation these parts have to the axis of inflorescence, that the outer series of this 

 perianthium is wanting, while its corresponding stamina exist, and that the 

 whole or part of the inner series is produced while its corresponding stamina 

 are generally wanting. This may, no doubt, actually be the case ; but as it 

 would be, at least, contrary to every analogy in Monocotyledonous plants, it 

 becomes in a certain degree probable that the inner or proper envelope of 

 Grasses, the calyx of Jussieu, notwithstanding the obliquity in the insertion of 

 its valves, forms in reality the outer series of the true perianthium, whose inner 

 series consists of the minute scales, never more than three in number, and in 

 which an irregularity in some degree analogous to that of the outer series gene- 

 rally exists. It is necessary to be aware of the tendency to suppression exist- 

 ing, as it were, in opposite directions in the two floral envelopes of Grasses, to 

 comprehend the real structure of many irregular genera of the order, and also 

 to understand the limits of the two great tribes into which I have proposed to 

 subdivide it. One of these tribes, which may be called Panicea^, comprehends 

 Ischsemum, Holcus, Andropogon, Anthistiria, Saccharum, Cenchrus, Isachne, 

 Panicum, Paspalum, Reimaria, Anthenantia, Monachne, Lappago, and several 

 other nearly related genera ; and its essential character consists in having al- 

 ways a locusta of two flowers, of which the lower or outer is uniformly imper- 

 fect, being either staminiferous or neuter, and then not unfrequently reduced to 

 a single valve. Ischaemum and Isachne are examples of this tribe in its most 

 perfect form, from which Anthenantia, Paspalum, and Reimaria, most remark- 

 ably deviate, in consequence of the suppression of certain parts : thus Anthe- 

 nantia (which is not correctly described by Palisot de Beauvois) differs from 

 those species of Panicum that have the lower flower neuter and bivalvular, in 

 being deprived of the outer valve of its gluma ; Paspalum differs from Anthe- 

 nantia in the want of the inner valve of its neuter flower, and from those species 

 of Panicum whose outer flower is univalvular, in the want of the outer valve of 

 its gluma ; and Reimaria differs from Paspalum in being entirely deprived of 

 its gluma. That this is the real structure of these genera may be proved by 

 a series of species connecting them with each other, and Panicum with Paspa- 

 lum. The second tribe, which may be called Poaceae, is more numerous than 

 Paniceae, and comprehends the greater part of the European genera, as well as 

 certain less extensive genera peculiar to the equinoctial countries ; it extends 

 also to the highest latitudes in which Phaenogamous plants have been found ; 

 but its maximum appears to be in the temperate climates, considerably beyond 

 the tropics. The locusta in this tribe may consist of 1,2, or of many "flowers ■ 

 and the 2-flowered genera are distinguished from Paniceae by the outer or 

 lower flower being always perfect, the tendency to imperfection in the locusta 

 existing in opposite directions in the two tribes. In conformity with this ten- 

 dency in Poaceae, the outer valve of the perianthium in the single-flowered ge- 

 nera is placed within that of the gluma, and in the many-flowered locusta the 

 upper flowers are frequently imperfect. There are, however, some exceptions 

 to this order of suppression, especially in Arundo Phragmites, Campulosus, and 

 some other genera, in which the outer flower is also imperfect ; but as all of 

 these have more than two flowers in their locusta, they are still readily distin- 

 guished from Paniceae." Brown in Flinders, 580. 



According to this view, in a locusta of several florets, the scales at its base, 

 or glumes, are bracteae, and each floret consists of a calyx formed of one sepal 

 remote from the rachis, and two cohering by their margins and next the rachis ; 



