76 METROPOLITAN PARK FLORA. 
on hill-tops, the long pistillate catkins conspicuous by the end 
of April :—B* and M, common:—S and B B, frequent. 
S. humilis <x discolor, Bebb. 
Same habitat as the parent species. M*, rare; near S. 
Reservoir. 
S. humilis, Marsh. Low Wittow. Prarrie WILLow. 
Dry or wet ground. 6B*, Chestnut Run path: — NM, fre- 
quent :— S *, occurs. 
S. tristis, Ait. Dwarr Gray WILLow. 
Sandy places, gravelly fields, low thickets and roadsides. 
B*, rare; N. slope of Rattlesnake Hill; W. of Sawcut Notch: 
— M*, occasional: — S*, Happy Valley. 
S. sericea, Marsh. Sitxy WILLow. 
Low ground. £B*, rare; Chestnut Run path, E. of Han- 
cock Hill: — M*, rare; N. side of Spot Pond. 
S. petiolaris, Smith. 
Low ground. M*, rare; fields round Spot Pond; meadow, 
N. of Bear Hill; S. end of S. Reservoir. 
S. PURPUREA, L. PuRPLE WILLOW. 
Adv. from Eu. in low ground. M, one tree in low land, S. 
W. of Pine Hill. 
S. cordata, Muhl. Herart-LEAVED WILLOW. 
Wet places, along streams and by damp roadsides. J, fre- 
quent : — M, occasional. 
S. cordata x sericea, Bebb. 
Low ground. B, swamp, N. E. of Hawk Hill. 
S. myrtilloides, L. 
Cold bogs. MV, occasional. 
POPULUS, Tourn. Poriar. ASPEN. 
P. tremuloides, Michx. ASPEN. 
Woods and roadsides; the most widely distributed tree in 
North America. B, occasional : — M, common. 

