1917] SHERFF—BIDENS 35 
At Gray Herbarium there occurs a single sheet (Coulter 375, 
Mexico) with three slender but well-developed specimens; the 
largest one, at the left, matching the type of B. angustissima, and 
the other two, at the right, matching the type of B. linifolia. 
From these it appears safe to say that B. linifolia will be found, 
on future field study, to be merely a simple-leaved state of B. 
angustissima. 
~BIDENS REFRACTA Brandeg., Zoe 1: 310. 1890.—Bidens 
riparia H.B.K. var. refracta O. E. Schulz, Urb. Symb. Antill. 
72 132. 19xt. 
Scuutz (loc. cit.) regarded this species as only a variety of 
B. riparia H.B.K., and he differentiates the two forms on the 
basis of fruit chasachele But an examination of many specimens 
of each form shows that the only genuine difference is in the foliage. 
B. refracta has tripartite leaves, while B. riparia has bipinnate 
leaves. This difference ScHutz seems to have overlooked. Indeed, 
he even refers to B. refracta a plant collected by Tonduz (no. 
13618, several fine specimens of which are in U.S. Nat. Herb., 
Herb. Brit. Mus., etc.) that is identical in foliage and other parts 
with the type and Bonpland cotype of B. riparia (in Herb. Mus. 
Hist. Nat. Paris). 
Of 22 collections of B. refracta studied so far, I have seen only _ 
one instance where the leaves were not of the tripartite kind. 
In this case (Jenman 5499, British Guiana, October 1889, in U.S. _ 
Nat. Herb.) the leaves are somewhat more divided, but still far 
from resembling those of true B. riparia. The probabilities are 
strong that B. refracta and B. riparia are entirely distinct species. 
BIDENs s H.B.K., Nov. Gen. et Spec. 4: 238. 1820.— 
Bidens tereticaulis De Prod? 5: 5938. 1836; Bidens antiguensis 
Coult., Bor. Gaz. 16: 100. 1891; Bidens tereticaulis DC. var. 
| antiguensis O. E. Schulz, Urb. Symb. Antill. 7: 142. 1911; Bidens — 
_ tereticaulis DC. var. sordida Greenm., Proc. Amer. Acad. 39: 
| 115. 1903; Bidens tereticaulis ‘De. var indivisa cere Proc. — . 
Bost. Soc. Nat. Hist. ae 270. 1904; Bidens Coreopsi. C. var. 
