110 GRAMINACE^. [Endogens. 



curious and important details relating to the structure and affinities of the genera of 

 Grasses. 



The stem of Grasses seems to be so much at variance in structure with that of other 

 Endogens, as to have led Agardh to remark, that it is the least monocotyledonous of all 

 Monocotyledonous plants. It is probable, however, that its pecuharity does not depend 

 so much upon any specific deviation from the ordinary laws of growth, as upon a separa- 

 tion of the parts at an early period of their growth. The stem of a Grass, it must be 

 remembered, exists in two different states, — that of the rhizome, and of the straw : 

 the rhizome, which is the true trunk ; and the straw, wliich may be considered a rami- 

 fication of it. The rliizome grows slowly, and differs in no respect from the stem of 

 other Monocotyledons, as is e\ident in that of the Bamboo. The straw, on the contrary, 

 which grows with great rapidity, is fistular, with a compact impervious diapliragm at 

 each articulation ; a fact which must be familiar to every one who has examined com, 

 or the joint of a Bamboo. In the beginning, when tliis straw was first developed, it was 

 a solid body like the rhizome, only infinitely smaller ; but in consequence of the great 

 rapidity of its development, the cellular tissue formed more slowly than the woody vas- 

 cular bmidles wliich it connects, and in consequence a separation takes place between 

 the latter and the foiTner, except at the articulations, where, by the action of the leaves, 

 and their axillary buds, is formed a plexus of vessels, which, gro\\'ing as rapidly as the 

 straw, distends, and therefore never separates in the centre. Something analogous to 

 this occTU's in the flowermg stem of the common Onion among Monocotyledons, and ui 

 UmbeUiferse among Dicotyledons. The stem of Grasses is not, howevex', always hoUow ; 

 in the Sugar Cane it is solid, as in common Endogens. 



The relation that exists between Palms and Grasses wiU be adverted to in speaking of 

 the former order : Nees v, Esenbeck considers Gi'asses to be a sort of Palms of a lower 

 grade. In reality, the habit of the genera Calamus and Bambusa is nearly alike ; the 

 inflorescence of Grasses may be considered to be the same as that of Palms, the floral 

 envelopes of the latter taken away, and only their liracts remakiing ; and, finally, the 

 leaves are formed upon exactly the same plan, with this difference only, that those of 

 Grasses are undi%dded. With Sedges, however, it is that Grasses are most properly 

 to be compared. While a manifest tendency, at least to the degree of verticillation 

 requisite to constitute a calyx, e^-idently takes place in the palese of Grasses, Sedges 

 are destitute of all trace of such a tendency, miless the opposite connate glumes of the 

 female flowers of Carex, or the hypog\Tious scales of certain Schoeni and others, be 

 considered an approach to the production of a perianth. For this reason. Grasses may 

 be considered plants in a higher state of evolution than Sedges. Independently of 

 this difference, the orders are usually known by the stems of Grasses being hollow, 

 those of Sedges soHd ; the leaves of Grasses ha^ing a ligula at the apex of their 

 sheath, which is split, wliile the sheath of Sedges is not split, and is destitute of 

 this ligula ; and, finally, the embryo of Grasses is external, lateral, and ^\^th a naked 

 plumule, while that of Sedges is undi\'ided and enclosed within the base of the 

 albumen. 



As nothing can be uninteresting which is connected with the habits of a tribe of such 

 vast importance to man, I extract the follo^\^ng accomit of the geograpliical distribution 

 of Grasses by Schouw, from Jameson's Philosophical Journal for ApriU 1825 : — " The 

 family is very numerous : Persoon's Synopsis contains 812 species, l-26th part of all the 

 plants therem enumerated. In the system of Roemer and Schultes there are 1800 ; 

 and, since tliis work, were it brought to a conclusion, would probably contain 40,000 in 

 all, it may be assumed that the Grasses form a 22nd part. It is more than probable, 

 however, that in futui'e the Grasses will increase in a larger ratio than the other phane- 

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

 Greater still will be theu' proportion to vegetation m general, when the number of indi- 

 viduals is taken into account ; for, in this respect, the greater number, nay perhaps 

 the whole of the other classes, are mferior. With regard to locality in such a large 

 family, very Httle can be advanced. Among the Grasses there are both land and water, 

 but no marme, plants. They occur in every soil, in society mth others, and alone ; the 

 last to such a degi'ee as entu'ely 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 occm* under the equator ; and Agrostis algida was one of the few 

 plants which Phipps met with on Spitzbergen. On the mountains of the south of 

 Europe, Poa disticha and other Grasses ascend almost to the snow line ; and, on the 

 Andes, this is also the case with Poa malulensis and dactyloides, Deyeuxia rigida and 

 Festuca dasyantha. 



" The greatest differences between tropical and extra-tropical Grasses appear to be 

 the following : — 1, The tropical Grasses acquire a much greater height, and occasionally 



