(166 ) 
Alnus tenuifolia Nutt. River bank opposite Dawson (Wil- 
liams). 
Alnus fruticosa Rupr. Dawson (Williams); Ft. Selkirk 
(Tarleton). Agrees with Asiatic specimens so determined, 
and seems distinct from Alnus Alno-Betula. 
Family URTICACEAE. 
Urtica gracilis Ait. Dawson (Williams). 
Family CHENOPODIACEAE. 
Bhitum capitatum L. Dawson (Williams); near Sixty- 
mile Creek (Tarleton). 
Family PoLYGONACEAE. 
Polygonum amphibium L.- Ft. Selkirk (Tarleton). 
Polygonum viviparum L. Bennett City (Williams); above 
Ft. Selkirk (Tarleton). 
Polygonum alpinum Alaskanum Small. Klondike below 
Bonanza (Williams) ; above Stewart River (Tarleton). 
Polygonum plumosum Small sp. nov. 
Perennial, deep green. Stems erect, 1-3 dm. tall, simple, 
glabrous: leaves few; blades thickish, sparingly pubescent 
beneath, those of the basal and lower stem-leaves ovate to 
oblong-ovate or broadly oblong, 2-5 cm. long, blunt or mark- 
edly obtuse, abruptly narrowed or subcordate at the base, 
as long as their petioles or shorter, those of the upper stem- 
leaves mostly oblong, short-petioled or nearly sessile, all 
more or less revolute and with prominent nerves about the 
edge: ocreae ample, prolonged into a narrowly funnelform 
sheath, persistent: racemes cylindric, 2-6 cm. long, dense: 
flowers persistent: calices rose-colored; lobes usually 5, 
broadly oblong or oval, 3.5-5 mm. long, obtuse or nearly 
truncate at the apex, often inequilateral: stamens exserted ; 
filaments slightly flattened; anthers dark brown or blackish: 
styles 3, elongated; stigmas capitate, minute: achenes 3- 
angled, ovoid or oval, 3-3.5 mm. long. 
Related to Polygonum bistortovdes Pursh; but it is stouter 
and more stocky in habit. It differs from P. dzstortozdes 
very conspicuously in its leathery and pubescent leaf-blades, 
