92 Rhodora {Marcu 
find that many of the plants from the Merrimac shores have the awns 
upwardly barbed. In the examination of hundreds of heads it has 
been found that with the exception of one single specimen all the 
achenes of an individual plant have similarly barbed awns. The 
material at hand shows that the Delaware River B. frondosa, var. 
anomaía is likewise essentially constant in its single morphological 
character, although as in the Merrimac Valley plant it shows no other 
feature by which it can be distinguished from the more ysual form. 
It is a striking coincidence that the habitat of Bidens frondosa, 
var. anomala and B. bidentoides, on brackish mudflats at the mouth of 
the Delaware River, should be so closely simulated by the brackish 
shores of the lower Merrimac where alone the plant discovered by 
Mr. Eaton has been found. B. frondosa, var. anomala, as already 
stated, however, has recently been found in Cape Breton and it is 
probable that the others will eventually prove to be of less restricted 
distribution than is at present known. 
The plant of the Merrimac shores first detected by a botanist 
whose keen observation is adding materially to our knowledge of a 
remarkaDle botanical area, may appropriately bear his name: — 
BipENs Eatoni. Annual, simple or freely branched, 2.5 to 6 dm. 
high: leaves simple, lanceolate, with long-acuminate tips and slender 
petiolar bases, coarsely and often deeply serrate, 5 to 15 cm. long: 
heads erect, cylindric or oblong, in fruit becoming obovoid, longer 
than broad: outer involucre usually of 3 to 5 foliaceous bracts 
slightly exceeding the disk: inner involucre mostly of 5 oblong blunt 
or barely mucronate conspicuously striate bracts about 1 cm. long, 
equalling the disk: rays none: disk flowers 15 to 25: achenes flat- 
tish; the inner 7 to 9 mm. long, 1 to 1.7 mm. broad, with well devel- 
oped but narrow midribs, linear-oblanceolate, usually with retrorse 
hairs on the margins; awns 2 to 4, downwardly barbed, the marginal 
longest, 3 to 4.3 mm. long, about equalling the pale yellow corollas. — 
Brackish shores of the Merrimac River, Newburyport, Massachusetts, 
Sept. 1902 (4. A. Eaton), Newburyport and Salisbury, Oct. 2, 1902 
(A. A. Eaton & M. L. Fernald). 
Var. fallax. Achenes and awns upwardly barbed.— With the 
species, but essentially constant in its single morphological character. 
EXPLANATION OF PLATE 45, Figs. 11-20. — Bidens Eatoni: Fig. 11, portion 
of flowering plant; fig. 12, outer achene; fig. 13, inner achene. 7. Eatoni, var. 
fallax: Fig. 14, inner achene. B. bidentoides: Fig. 15, flowering head; fig. 16, 
inner achene. Z. connata: Fig. 17, flowering head; fig. 18, inner achene. B. 
comosa: Fig. 19, flowering head; fig. 2c, inner achene. 
Vol. 5, no. 50, including pages 41 to 76 and plate 44 was issued 
25 February, 1903. 
