Botany. 281 



leaf tapering gradually to the petiole, and similar but smaller 

 sessile stem leaves. With such inconsistencies as these between 

 descriptions and figures it is of course impossible to form any 

 just opinion as to the validity of the species which are here de- 

 scribed. 



Throughout the work, as was expected, the tendency seems to 

 be to regard as species many forms which have often been re- 

 garded merely as varieties. In many cases this course seems the 

 proper one in view of recent studies and increased data. For 

 instance, the separation of some forms from Pyrola rotundifolia 

 seems quite proper: P. asarifolia, at any rate, is a plant with 

 very different foliage and range, and its rose-colored flowers are 

 expanded some weeks before those of the more southern white 

 P. rotundifolia. Amelanchier rotundifolia, a species of north- 

 ern river-banks, blooms in late May and in June, and matures its 

 fruit in late August or September, long after that of A. Cana- 

 densis has fallen. It is a pleasure to see this plant put on the 

 same basis as A. Canadensis and A. oligoearpa ; but it is not 

 quite clear how the Rochester Code allows the specific name 

 rotundifolia, first applied as a varietal name to this plant in 1808, 

 when there is already the European A. rotundifolia, Decaisne, 

 founded upon Cratwgus rotundifolia, Lam. Encyc, i, 84 (1783). 



On the other hand, many of the old varieties, here raised to 

 specific rank, seem to have less upon which to rest. The IIous- 

 tonias, H. ciliolata and II. longifolia, already referred to, are 

 well marked as extreme variations from II. purpurea, but with a 

 large proportion of specimens falling between these different 

 forms and showing many combinations of their characters, it is 

 hard to see how they can be counted as of specific rank. In 

 treating jSalsola, Professor Britton keeps apart as species /S. Ifali 

 and S. Tragus. How, after the observations of M. Constantin,* 

 these plants can be regarded as more than forms of the same 

 species, is not easy to understand. According to M. Constantin, 

 when the seashore Scdsola Kali, with coriaceous calyx and fleshy 

 leaves, creeps up the rivers, the calyx becomes membranous and 

 the leaves less fleshy, thus passing directly into the so-called S. 

 Tragus. Contrasted with the treatment of ISalsola the case of 

 one of the common aquatics, Myriophyttum humile (31. am- 

 biguum) maybe taken. One form of the plant is very small with 

 short leaves, and it grows in shores (31. ambiguum, var. limoswn, 

 Ton*.). Another form, appearing very different, becomes even 

 two feet long, has fine elongate-capillary leaves and grows in 

 water (31. ambiguum, var. capillaceum, Torr. and Gray.) Yet 

 Professor Britton (in this as in his general treatment of the group, 

 closely following the late Doctor Morong) gives no recognition 

 to these extreme forms, considering them " only conditions of 

 the plant dependent upon its environment." What but environ- 

 ment, we mav ask, has produced the peculiarities of Salsola 

 Tragus? 



* Jour, de Bot , 1887. 44. 



Am. Jour. Sci.— Fourth Series, Vol. VI, No. 33. — September, 1898, 

 19 



