837 



LEJEUNEA ROSSETTIANA Massal. 

 By Richaed Speuoe, Ph.D. 



This is truly a most distinct and interesting new species. 

 From L. calcarea Lib., its nearest European ally, it differs, not 

 merely by the absence of the leaf-style, or process at the exterior 

 base of the lobule, but by the entire outer surface of the leaf, 

 lobule included, being heset with longer and denser papillae ; 

 whereas in L. calcarea the lobule is naked and merely reticulate 

 with the plane cellules. The lobule is, besides, larger and more 

 rhombic, and armed with two to four (usually three) sharp teeth at 

 and near the apex, which teeth in L. calcarea are either wanting or 

 are reduced to mere denticulations. The upper lobe (or leaf 

 proper) is more briefly and narrowly acuminate. Finally, the 

 inflorescence appears dioicous, while in L. calcarea it is normally 

 monoicous, althoagh unisexual plants are not infrequent. 



Perhaps the very nearest ally of L. Russettiana is the Javan 

 L. venusta Sande-Lacoste, Hep. Jav. tab, xii., which has quite the 

 same habit and general character ; each leaf-cell, of both lobe and 

 lobule, bearing a long papilla ; underleaves and styles equally 

 absent, &c. It differs in the obtuse leaves and the smaller, more 

 inflated, entire lobule. Another species of the same group 

 (Cololejeunea, Hep. Am.), agreeing with ours in the scabrous leaves 

 and perianth, is L. erigens Spruce MS., which I gathered in some 

 abundance in North Brazil and in conterminous parts of Venezuela ; 

 but this is a larger species, and the leaves, &c., are minutely 

 muricate rather than echinate or papillose. 



The styliform appendage to the leaves of L. calcarea seems to 

 have been first noticed by Nees, nearly 60 years ago, who con- 

 sidered it a rudimentary stipule, only occasionally present. It has 

 been correctly described by Lindberg in his ' Hepaticse in Hibernia 

 lectae ' (1875) ; and he supposed it analogous to the leaf-style of 

 Frullania. A good while ago I came to the conclusion that it was a 

 unicrural, or dimidiate, stipule, from the following considerations. 

 The so-called "stipules " of the leafy Hepaticae are under-leaves, each 

 attached to a side-leaf, along one side of the stem only ; and not 

 merely adjacent to it, but in most cases actually connate with it at 

 the base, as can be seen in every genus where stipules exist. In those 

 groups of Lejeunea which I have called Drepanolejeimea and Lepto- 

 lejeunea the stipules are usually cloven nearly to the base into two 

 divergent, subulate or setaceous, segments or crura, each often of a 

 single row of cellules. When one of the two crura is obsolete, or 

 undeveloped, we have a dimidiate, or unicrural, stipule, exactly 

 corresponding in form and insertion to the style of certain Colo- 

 lejeunea. 



In all stipuliferous Hepaticae a tuft of radicles is (or may be) 

 emitted from the base of each stipule, so that the leaves are 

 (normally) twice as numerous as the stipules or the root-tufts. But 

 in the Cololejennem rootlets are (or may be) developed at the base of 

 every leaf, and that brings them into close relationship to two 



Journal of Botany.— Vol. 27. [Nov. 1889.] z 



