1915] Fernald & St. John,— Species and Varieties of Bidens 21 
and with more numerous teeth. In its nearest relative, B. Eaton, 
the leaves are all slender-petioled, the heads slender-cylindric, the 
inner involucre in well developed heads 1-1.5 cm. long, the chaff 
dark-striate, and the achenes usually 4-awned, the inner ones 7-9 mm. 
long and scarcely or only faintly striate; while in the plant from Maine 
the upper leaves are sessile, the inner involucre of well developed 
heads 5-8 mm. long, and the achenes are copiously channeled. 
In its foliage and in the breadth of the larger heads the plant from 
the lower Androscoggin and Kennebec closely simulates extreme 
slender forms of B. cernua L., but that species has the nodding heads 
depressed-hemispherical in outline with a nearly flat base, the outer 
foliaceous bracts spreading, the chaff dark-striate, and the 4-awned 
achenes strongly 4-angled at summit and tuberculate on the angles. 
In the Maine plant, however, the erect heads have somewhat turbinate 
involucres, with erect outer foliaceous bracts, and the 2-awned achenes 
are flat and without tuberculate hairs. 
Differing in all its essential characters from the three species which 
it most nearly resembles, the plant from the estuary of the Kennebec 
and Androscoggin Rivers seems to be another of the localized estuary 
species comparable with B. bidentoides (Nutt) Britton, known only 
from the estuary of the Delaware, B. Eatoni Fernald, known only 
from the estuary of the Merrimac, and B. hyperborea Greene of the 
river-estuaries entering the Gulf of St. Lawrence and James Bay. 
The Maine plant we propose as 
3 mm. longis retrorse barbatis, achaeniis exterioribus 5 mm. longis, 
interioribus 6 mm. i 
b. erect: in ina 
cts strongly ascending, glabrous, linear-lanceolate, acute or sub- 
