1918] Fernald,— Bidens hyperborea and B. colpophila 149 
species of very disrupted range and, presumably on account of the 
extreme isolation of its habitats, it presents several pronounced geo- 
graphic variants. These may be defined as follows: 
Outer achenes 4.2-5 mm. long; the inner 6-7 mm. long, with marginal awns 
1.8-3 mm. long. 
Plant simple and monocephalous: leaves oblanceolate and blunt, sub- 
entire or obscurely toothed; the longer 4 cm. long: bracts of the 
outer involucre 1.5-1.7 cm. long, only slightly exceeding the disk. 
B. hyperborea (typical). 
Stem branching; the branches strongly ascending, few to very numerous: 
leaves linear to oblanceolate, attenuate, commonly with 3-10 
pairs of sharp teeth; the primary leaves 0.5-1.2 dm. long: bracts 
of the outer involucre 1.5-4 cm. long.......... var. colpophila. 
Outer achenes 6-8.5 mm. long; the inner 7.5-10 mm. long, with marginal awns 
3-5 mm. long. 
Tall, 3-7 dm. high, with strongly ascending branches: leaves thin, with 
midrib prominent beneath, long-attenuate at tip; the primary ones 
0.6-1.4 dm. long, with numerous sharp teeth: bracts of outer invo- 
lucre 4-9, linear to lanceolate, acute or acuminate, entire, 1.5-3.5 
ee eae var. cathancensis. 
B. HYPERBOREA Greene, Pittonia iv. 257 (1901).— The typical form 
of the species is known only from the original collection from Rupert 
House, James Bay, September 5, 1885, J. M. Macoun, no. 12056. 
Var. colpophila (Fernald & St. John), n. comb. B. colpophila 
Fernald & St. John, Ruopora, xvii. 21 (1915).— Tidal flats and bor- 
ders of salt marshes, Maine and Massachusetts. The following 
specimens may be cited: Marne: abundant on tidal mud-flats of the 
Penobscot River, Bangor, September 7, 1916, Fernald & Long, nos. 
14829, 14830; very abundant on tidal mud-flats at the mouth of Reed 
Brook, Hampden, September 8, 1916, Fernald & Long, nos. 14831, 
14832, also in Pl. Exsicc. Gray. no. 296; tidal mud-flats at mouth of 
Souadabscook Stream, Hampden, September 11, 1916, Fernald & 
Long, nos. 14833, 14834; borders of salt marsh, Back River Creek, 
Woolwich, September 15, 1916, Fernald & Long, no. 14826; above 
tide-limit at edge of marsh and among sedges and rushes of salt marsh, 
- Winnegance Creek, Phippsburg, August 23, 1909, Fernald, nos. 2248, 
2249; Cow Island, Topsham, August, 1910, Kate Furbish; bank of 
= Androscoggin River, Brunswick, August 13, 1911, C. H. Bissell; 
~ August 22, 1911, R. A. Ware, no. 4230. Massacnuserts: brackish 
muddy shore of the Merrimac, Newburyport, October 2, 1902, A. A. 
Eaton & M. L. Fernald. ; 
Var. cathancensis, n. var., planta erecta 3-7 dm. alta ramibus valde 
adscendentibus; foliis tenuibus lineari-oblanceolatis attenuato-acumi- 
natis argute serratis, primariis 0.6-1.4 dm. longis, costa subtus promi- 
