HOFFMANN: FLORA OF BERKSHIRE COUNTY. 347 
P. serpentaria Pursh. Lion's-foot; Gall-of-the-earth. — Dry 
thicket, Sheffield. 
P. trifoliata (Cass.) Fernald. Gall-of-the-earth. — Woods; 
common. Summit of Greylock, 3400 feet. 
RUDBECKIA. Cone-flower. 
R. HiRTA L. Black-eyed Susan; Yellow Daisy. — Fields; 
common. Not mentioned by Dewey. Introduced from the West 
after 1850. 
The following forms have been noted : — 
a. Rays greenish or streaked with green. 
h. Rays purple at base. 
c. Heads with green chaff replacing the flowers. 
R. laciniata L. Tall Coxe-flower. — Borders of streams, moist 
banks and upland meadows; frequent. The double form, cultivated 
under the name " Golden Glow " occasional as an escape. 
SENECIO. Groundsel; Ragwort. 
S. aureus L. Golden Ragwort. — Low woods, wet meadows and 
swamps; common. 
S. obovatus Muhl. — Rocky woods, moist banks and ledges; com- 
mon in calcareous soil, and frequent elsewhere. 
S. VULGARIS L. — Waste ground, Williamstown. 
SERICOCARPUS. White-topped Aster. 
S. asteroides (L.) BSP. — Dry open woods; frequent in the south- 
ern part of the valley. 
SOLIDAGO. GoLDEN-ROD. 
Key to Solidago. 
a. Heads clustered along the axils of the leaves or in spikes or jianieles, not in 
flat-topped (■orynil)s. 
b. Bracts of rigid involucre with abruptly si)reading herl)aceous tips; 
heads in clusters or compactly clustered racemes, disposed in a dense 
somewhat leafy ami interrupted wand-like compound spike; local. 
>S. sqiiarrosa. 
b'. Bracts of the involucre without green tips and api)ressed. 
c. Heads clustered along the axils oi the leaves, or in wantl-like, or 
pyramidal compact panicles, not in spreading ojien iianides. 
