297 



a straw or the joint of a Bamboo. In the beginning, when this culm 

 was first developed, it was a solid body like the rhizoma, only infinitely 

 smaller ; but in consequence of the great rapidity of its developemcnt, the 

 cellular tissue forms more slowly than the woody vascular bundles which it 

 connects, and in consequence a separation takes place between the latter 

 and the former, except at the articulations, where, by the action of the leaves 

 and their axillary buds, is formed a plexus of vessels, which grows as rapidly 

 as the culm distends, and therefore never separates in the centre. Some- 

 thing analogous to this occurs in the flowering stem of the common Onion 

 among Monocotyledons, and in Umbelliferse among Dicotyledons. 



The strict relation that exists between Palms and Grasses has been already 

 adverted to in speaking of the former order : hence Nees considers Grasses to 

 be a sort of Palms of a lower grade. In reality, the habit of the Calamus and 

 Bambusa genera is nearly alike ; the inflorescence of Grasses may be consi- 

 dered to be the same as that of Palms, the floral envelopes of the latter taken 

 away, and only their bracteee remaining; and, finally, their leaves are formed 

 upon exactly the same plan, with this difference only, that those of Grasses 

 are undivided. With Cyperacege, however, it is that Grasses are most properly 

 to be compared : while a manifest tendency, at least to the degree of verti- 

 cillation requisite to constitute a calyx, evidently takes place in the palese 

 of Grasses, Cyperaceas are destitute of all trace of such a tendency, unless 

 the opposite connate glumes of the female flowers of Carex, or the hypogy- 

 nous scales of certain Schasnxis' and others,, be considered an approach to the 

 production of a perianthium. For this reason. Grasses are to be considered 

 plants in a higher state of evolution than Cyperacece. Independently of this 

 diflerence, the orders are readily known by the stems of Grasses being round, 

 those of Cyperacese angular; the leaves of Grasses having a ligula at the apex 

 of their sheath, which is split, while the sheath of Cyperaceee is not split, and 

 is destitute of this ligula; and, finally, the embryo of the two is at variance 

 both in structure and position. With Asphodelese their relationship con- 

 sists in nothing more than the tendency to branch which is observable in 

 part of that order. 



Geography. As nothing can be uninteresting which is connected with 

 the habits of a tribe of such vast importance to man, I extract the following 

 account of the geographical distribution of Grasses by Schouw, from Pro- 

 fessor Jameson's Philosophical Journal for April 1825 : — 



" The family is very numerous : Persoon's Synopsis contains 812 species, 

 l-26th part of all the plants therein enumerated. In the system of Roemer 

 and Schultes there are 1800; and, since this work, were it brought to a 

 conclusion, would probably contain 40,000 in all, it may be assumed that 

 the Grasses form a 22d part. It is more than probable, however, that in 

 future the Grasses will increase in a larger ratio than the other phsenerogamic 

 plants, and that perhaps the just proportion will be as 1 to 20, or as 1 to 16. 

 Greater still will be their proportion to vegetation in general, when the num- 

 ber of individuals is taken into account; for, in this respect, the greater 

 number, nay, perhaps the whole, of the other classes are inferior. 



" With regard to locality in such a large family, very little can be ad- 

 vanced. Among the Grasses there are both land and water, but no marine, 

 plants. They occur in every soil, in society with others, and alone ; the last 

 to such a degree as entirely to occupy considerable districts. Sand appears 

 to be less favourable to this class ; but even this has species nearly peculiar to 

 itself. 



" The diffusion of this family has almost no other limits than those of the 

 whole vegetable kingdom. Grasses occur under the equator ; and Agrostis 

 algida was one of the few plants which Phipps met with on Spitzbergen. 



