305 



We have seen that in Vascular plants the great divisions of Monocotyle- 

 dons and Dicotyledons, or of Endogenous and Exogenous plants, have been 

 satisfactorily established. In Ccllulares attempts have been made to establish 

 parallel divisions, but I fear, without much success ; these plants appearing to 

 be analogous rather to one of the two divisions of Vasculares, than to compre- 

 hend within themselves groups of equally different organization. 



M. Decandolle refers Ferns and their immediate allies to Endogenous plants, 

 and separates the remainder into Foliacecs, or plants with leafy expansions, 

 and Aplujllce, or those destitute of leaves : but to the first of these there are 

 grave objections ; the second nearly corresponds with the arrangement here 

 adopted. 



Agardh, in 1821, divided them thus : Acotyledone^:, or leafless plants, 

 with all the parts confluent, the colour not herbaceous, with no stamens and 

 pistils, and propagated by sporidia. (Spoiidium est corculum nudum, radicula, 

 cotyledone, et hilo destitutum. JLph. 71.) Pseudocotyledone.5:, or leafy 

 plants, the parts of which are sometimes confluent, the colour green, with an 

 attempt at producing stamens and pistils, and propagated by sporules enclosed 

 in capsules. (Spora est corculum perispermio (?) et membrana simplici hilo 

 destitute inclusum, germinalione cotyledonidium (analogon cotyledoni folium) 

 explicans. Ibid. 71.) To Acotyledoneae he refers only Fungi, Lichens, and 

 Algae, and comprehends the remainder in Pseudocotyledoneae. This arrange- 

 ment is undoubtedly natural, but it is liable to objection, on the ground, that 

 although the two groups are distinct, yet it is extremely uncertain whether the 

 characters assigned to each are founded upon accurate observation. For in- 

 stance, the distinction drawn between their modes of reproduction or germina- 

 tion is altogether arbitrary. It is well known that Mosses and Confervas are so 

 similar when germinating, that young plants of the former have been described 

 as belonging to the latter tribe (see Mr. Drummond's paper in the Transactions 

 of the Linnozan Society, 15. p. 20.) ; and yet one is said to increase by sporules, 

 and the other by sporidia. The confluence of all the parts in Acotyledoneae, 

 and the separation of them in Pseudocotyledoneae, will not distinguish them ; 

 witness Marchantia, Riccia, &c. in the latter, and such species as Caulerpa 

 hypnoides in the former. Colour is a still less satisfactory difference : for ex- 

 ample, what green have we in Mosses or Ferns, or other Pseudocofyledonea?, 

 more intense than in Ulva and numerous Algae among Acotyledoneae ? As to 

 a supposed tendency to developement of stamens and pistils- in one and not in 

 the other, this may possibly be the case ; but it is no character of the two 

 groups ; for what better proof have we of any such tendency existing in Lyco- 

 podineae or Hepaticae, than in Lichens. 



Fries, in his Plantoz Homonemea ■, adopts these divisions, but assigns them 

 new names and characters. He calls the Acotyledoneae of Agardh Homone- 

 mea, and the Pseudocotyledoneae he terms Heteronemea, with the following 

 characters : Heteronemea. Germinating filaments, combining in a hetero- 

 geneous body, with some analogy to the difference of stamens and pistils. Tis- 

 sue consisting of cellules regularly united. Homonemea. Germinating fila- 

 ments, either distinct or combining in a homogeneous bod_y, with no trace of 

 sexual differences. Tissue consisting of anomalous, somewhat filamentous cel- 

 lules. — I scarcely know whether to consider these definitions more satisfactory 

 than those of Agardh ; perhaps they are : but their fault is evidently that of 

 being too hypothetical, and of not distinctly deciding the position of Hepatica?. 



Struck, perhaps, with this objection, M. Adolphe Brongniart has more re- 

 cently proposed a triple division of Cellular plants, in the following manner : 

 I. Neither vessels nor foliaceous appendages ; no trace of stamens and pistils : 

 sporules contained in indehiscent capsules, or bursting irregularly, with no kind 

 of proper integument. These answer to the Acotyledones of Agardh and the 



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