BICKNELL: FERNS AND FLOWERING PLANTS OF NANTUCKET 119 
‘it is a hybrid is indicated by its locally sporadic occurrence and its 
relationship to other Nantucket forms that are not less certainly 
of hybrid origin. Somewhat at variance with its more character- 
istic forms is a weaker, less spiny plant, having paler green leaves 
with less rounded leaflets, which though quite possibly a phase 
of the same cross, may include some other element. 
* RUBUS FLAGELLARIS X FRONDOSUS. — 
I have placed here a blackberry nearly related to R. argutus X 
flagellaris, but differing as follows: Stems more slender and terete, 
sparingly if at all branched, less purplish in color, more sparsely 
and less strongly armed with shorter prickles; pubescence 
less dense and tomentulose, often scant; leaves thinner and 
paler green, the marginal pattern more serrate and often more 
coarsely cut; primary leaves smaller, the odd leaflets broadly 
ovate to ovate-oblong, often with somewhat narrowed base; 
flowering branchlets and pedicels more slender. 
This plant, like the preceding, suggests close relationship to 
R. Baileyanus X frondosus but is obviously not the same. It 
appears to differ muchas a hybrid of R. frondosus might be sup- 
posed to do where R. flagellaris had replaced R. Baileyanus as one 
of the parents. Certain specimens which it seems necessary to refer 
here appear too close to examples of R. argutus X flagellaris, but 
other specimens are not to be reconciled with that cross. The 
plant is, in fact, somewhat intermediate between R. argutus X 
flagellaris and R. Baileyanus X frondosus. The very close re- 
lationship of many of these plants and the essential identity of 
certain of their characters lend support to the probability of their 
being crosses of nearly related parents. 
* RUBUS FRONDOSUS X NIGRICANS. 
R. abbrevians Bld. 
Sometimes erect but more often recurved and spreading or 
partly trailing, simple or sparingly branched; stems often becom- 
ing deep red-purple, subterete to somewhat angled, densely 
armed, or sometimes only sparsely armed in weak plants, prickles 
of very unequal size, erect or slightly retrorse, straight or nearly 
so, acicular, the larger becoming 6 mm. long from a broadened 
base, the smaller diminishing into gland-tipped hairs, which usually 
invest the upper part of the stem; primary leaves 5-foliolate 
