BICKNELL: FERNS AND FLOWERING PLANTS OF NANTUCKET 107 
the plant is sometimes quite prostrate, in better soils erect and 
recurving. Occasionally in damp shaded thickets, as on Rattle- 
snake Bank and in Pocomo, its stems ascending through the shrub- 
bery become reclined and long-trailing over the bushes five or 
six feet above the ground. Such plants are usually characterized 
by thin and light green, long-attenuate, narrow leaves, but they 
pass imperceptibly into the more stocky and pubescent broader- 
leaved and darker green plant of more open ground. First 
flowers June 8, 1908; last flowers June 26, 1910; ripe fruit August 6, 
1906. 
The prevailing form of this species on Nantucket is recogniz- 
able as the plant which has been described as R. recurvans Bld. 
Should it be held that this plant is sufficiently divergent to merit 
specific standing, the nomenclature of the several hybrids of R. 
frondosus herein described should be correspondingly modified. 
* RUBUS NIGRICANS Rydb. 
The prevailing form on Nantucket of this, perhaps the most 
widely variable of all our blackberries, is notably different from 
any form of the plant I have met with elsewhere. Northward, or 
at higher altitudes, the species seems to tend towards delicate 
forms, often only sparsely bristly, with narrower and glabrate, 
brighter green leaflets; southward in coastwise swamps, or inland, 
coarser forms are found with larger, duller green, more pubescent 
leaves, and a more pronounced development of bristly arma- 
ture, which is copiously glandular-hairy throughout. Forms 
similar to these are found occasionally on Nantucket, but the 
more usual form on the island is marked, in its extreme develop- 
ment, by its almost non-glandular character ; dark purple, more or 
less angled stem, armed with strong, straight, acicular prickles, 
which are often swollen at the base; thick and shining glabrate. 
leaflets, mostly suborbicular and obtuse and somewhat crenate- 
dentate; and a bristly almost non-glandular inflorescence, the 
calyx lobes glabrate to tomentulose and with or without setae 
and glandular hairs. This plant passes on the one hand into the 
coarser, more pubescent form above referred to with subterete, 
densely bristly and glandular-haired stems and narrower, obovate- 
oblong, acute, serrate leaflets, and on the other hand into a re- 
