294 



cessary to give them here. I have a monstrous Wheat, specimens of which I 

 communicated in 1830 To MT Kunth and others, in which the midrib of the 

 lower palea actually becomes saccate towards the apex, bearing an imperfect 

 floret, with stamens, ovarium, and hypogynous scales, in its cavity. What 

 we know of the tendency to special developement of buds in the margins of 

 leaves, and, from Ferns and the observations of M. Turpin, in the whole sub- 

 stance of certain monocotyledonous leaves, there is nothing in this fact to ex- 

 cite surprise or to give rise to new theories ; but it is worth mentioning as the 

 only instance upon record of a flower-bud with stamens and pistils being deve- 

 loped under such circumstances. 



The embryo is here described in conformity with the views that are most 

 commonly taken of its nature ; that is to say, it is considered to consist of a di- 

 lated lenticular cotyledon applied to the albumen on one side, and bearing a 

 naked plumula on the other side, next the testa. It is proper, however, to re- 

 mark, that the opinion of the late M. Richard, that the part commonly called 

 cotyledon is a peculiar process, and that the plumula is a body contained within 

 the apparent plumula, has been lately adopted by Professor Nees v. Esenbeck, 

 in his Agroslologia Brasiliensis, but with some difference. Richard considered 

 the cotyledon to be a part of the radicle, to which he gave the name of macro- 

 podal, in consequence of its great supposed enlargement in Grasses and some 

 other families ; Nees v. Esenbeck, on the contrary, seems to entertain the 

 opinion that this cotyledon is a special organ, for which he retains Richard's 

 name of hypoblastus, although he does not adopt the view that botanist took 

 of its nature. But I think if we consider the improbability of any special or- 

 gan being provided for Grasses, which is not found elsewhere, and if we consi- 

 der how nearly alike are the embryos of Grasses and certain Aroidea?, in which 

 the plumula lies within a cleft of the cotyledon, it is impossible to doubt the 

 identity of the hypoblastus of Richard and Nees v. Esenbeck, and the cotyle- 

 dons of other Monocotyledons. Indeed, the latter himself appears, in one place, 

 to hesitate about the accuracy of distinguishing them, when he says (p. 9), 

 " Turn vero hypoblastus pars qucedam habenda est cotyledoni analoga, magis- 

 que ad interiora seminis quam ad externam corculi evolntionem spectans." 



The structure of the stem of Grasses is so much at variance, apparently, 

 with that of other Endogenous plants, as to have led Professor Agardh to remark, 

 that it is the least monocotyledonous of all Monocotyledonous plants. It is 

 probable, however, that its peculiarity does not depend so much upon any specific 

 deviation from the ordinary laws of growth in Endogenee,as upon a separation 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 rhizoma, and of the 

 culm: the rhizoma, which is the true trunk; and the culm, which maybe 

 considered ramifications of it. The rhizoma grows slowly,, and differs in no 

 respect from the stem of other Monocotyledon.-, as i.< e\ ident in that of the Bam 

 boo. The culm, on the contrary, which grows with great rapidity', is fistular, 

 with a compact impervious diaphragm at each articulation ; a fact which must 

 be familiar to every one who has examined 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 developement, the. cellular tissue forms more slowly than the woody vascu- 

 lar 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. Something analogous to this occurs in the flowering stem of the 

 common Onion among Monocotyledons, and in Umbclliferce among Dicotyle- 

 dons 



