TERMINOLOGY IN MONOCOTYLEDONS. 501 



or axile embryo in two orders (Pandauese and Typhaceae) ; exalbu- 

 minoua in one (Naiadeae) ; albuminous in some genera, exalbumi- 

 nous in otbers in the remaining two (Aroideae and Lemnaceaj). 

 The distinctive characters of these several orders have been too 

 well marked out in various works to require any comment on 

 the present occasion, except that I cannot agree with Kunth in 

 considering each stamen and each carpel, in Potomogeton and its 

 allies, as a separate unisexual flower, and that I would include in 

 Naiades both Triglochin and Scheuchzeria. 



Alismaceae form a small order very puzzling as to its aflinities. 

 The objections to associating it with Hydrocharkleae, as frequently 

 proposed, have been above adverted to. The double perianth of 

 the majority of genera (reduced to two petaloid segments in 

 Aponogeton) might refer it to Coronariae, were it not for the apo- 

 carpous ovary and exaibuminous embryo, which bring it so near 

 to Naiadeae ; whilst it differs from the live preceding orders of 

 Nudiflorae, not only in the development of the perianth, but also 

 in the stamens, which, even when definite, are not opposed to the 

 perianth-segments, and in which the filaments are usually slender, 

 and the anther-cells always opening inwards. On the whole it 

 seems best to regard Alismaceae as an anomalous order, connect- 

 ing in some measure Naiadeae with Hydrocharideae, but more 

 nearly allied to Nudiflorae than to any other series or alliance. 



The Glumales are a group of orders established by Lindley and 

 very generally recognized, although within different limits accord- 

 ing to the special views entertained by different botanists, and 

 with verv different meanings attached to the term glume. Nor, 

 indeed, can any limits or definition be given which shall admit of 

 no exception. Generally speaking, in the five orders to which, 

 after Lindley, I would limit the alliance (Eriocauleae, Centrole- 

 pide*, Eestiaceae, Cyperaceae, and Gramineaj) the flowers are ses- 

 sile or nearly so, and solitary within imbricate dry bracts termed 

 glumes, forming heads or spikelets, which may be solitary or vari- 

 ously combined in heads, spikes, racemes, or panicles ; the perianth 

 is scarious or glume-like, and concealed under the glumes or en- 

 tirely deficient ; the ovary is free and uniovulate, or divided into 

 uniovulate cells ; and the seeds are albuminous. This definition 

 excludes the Xyridea? and Juncaceae referred to the group by 

 Steudel ; for the" former, although, like Johnsonia and its allies 

 among Liliaceje, they may have the imbricate dry bracts of Glu- 

 males, have nevertheless a very different ovary as well as the large 



