ENGELMANN — N. AM. SP. OP GENUS JUNCUS. 425 



will stand in place of expensive plates, and will, it is believed, 

 be far preferable to them. 



Arrangement. — The numerous species of the Genus Juncus* 

 have been divided into sections according to characters taken 

 from their organs of vegetation, their stems and leaves and 

 also their inflorescence, more than from the differences found 

 in their flowers or fruits. In these most essential parts all 

 the species show a remarkable uniformity, which will only- 

 permit us to make use of them to characterize minor divisions, 

 and for specific diagnosis. Desvaux (Journ. Bot., Vol. I., 

 Paris, 1808) had already separated our Juncus repens, on 

 account of a peculiarity in the dehiscence of the capsule, and 

 some alpine species, because of their long-tailed seeds, as 

 two distinct genera, Cephaloxys and Marsippospermum. 

 But we know now that other species of far different alliance 

 form a transition from the ordinary loculicidal to the sep- 

 tifragal dehiscence, and that species of all forms and sections, 

 and otherwise very dissimilar among themselves, have tailed 

 seeds, and that others exhibit all the transitions from 

 the tailed and loosely tunicated to the merely pointed and 

 closely coated seed. From the following it will appear that 

 these genera cannot stand even as sections. 



Vegetative Organs. — The different forms of the rootstalks, 

 and of the stems and leaves of these plants, are so well 

 known that I need not here dwell upon them; by their dif- 

 ferences the principal types of Junci are best characterized; 

 those that produce no leaves or leaves equal to the stem itself, 

 those that have channelled or flattened leaves, and those that 

 bear knotted leaves. But I must say that we have forms that 

 seem to bridge over these apparently well marked distinctions, 

 and wbich again prove that nature knows nothing of our 

 systematic subtleties, and that our systems are only an imper- 

 fect aid for our limited comprehension. To give an example 

 — no section of Juncus seemed to be better characterized and 

 more natural than that of the true Junci with naked stems 

 and so-called lateral inflorescence. To this section we are 

 bound to refer J. Drummondi and J. Hallii, while J. biglu- 

 mis, which can scarcely be separated from them, is, in all our 

 systematic works, far removed from them. Again, J. Vaseyi 

 comes so close to J. Ilallii that we would hesitate whether 

 to class it with this or with the similar looking but flat-leaved 

 J. tenuis, if J. Greenii did not unite it more directly with 

 the latter one. 



The form of leaves is not quite constant. While those of the 

 articulate Junci are usually described as terete or compress- 

 ed-terete, the observations of our southern botanists prove 



* Steudel, in bisPlantae Glumacese, 1855, enumerates 196 species, many 

 of them, however, undoubtedly nominal ones. 



