Hybridism and Classification in the Genus Rosa , 163 
If we make an analysis on the basis of (1) hairiness of the 
leaflets (H), glabrousness (h), (2) biserration (B), not biserrate (b), 
(3) the presence of glands on the leaflets (G), the absence of foliar 
glands (g), (4) hispid peduncles (S) and smooth peduncles (s), then 
there are sixteen theoretical combinations to consider:—HBGS, 
HBGs, HBgS, HBgs, HbGS, HbGs, HbgS, Hbgs, hBGS, hBGs, 
hBgS, hBgs, hbGS, hbGs, hbgS, and hbgs. We may apply these 
combinations first to the canina-dumetorum groups; the last 
eight containing h will be glabrous and thus correspond to canina 
forms. Six of the eight combinations have been named. R. lute - 
tiana Lem. is the form hbgs,, and R. andegavensis Bast, corresponds 
to the hbgS form. The combination hBgs covers R. dumalis 
Bechst., while similar plants with hispid peduncles come under the 
hBgS form, known as R. verticillacantha Mer. The two biserrate 
“ species ” with subfoliar glands are R. scabrata Crep. and R. 
Blondceana Rip., the former with smooth peduncles, i.e. hBGs, the 
latter with hispid peduncles, i.e. hBGS. The combinations hbGS 
and hbGs are without names. Four of the eight combinations 
containing H have been met with in Britain and comprise the series 
of forms which are classified under the dumetorum group since 
the leaves are hairy. The Hbgs form corresponds to R. urbica 
L£m., and to the HbgS combination the name R. Deseglisei Bor. 
applies. Of the biserrate hairy forms, R. arvatica Bak. p.p. 
corresponds to HBgs, while the HBgS combination is referable to 
R. canina var. aciculata Rouy. Four forms having subfoliar glands, 
HBGS, HBGs, HbGS and HbGs, are so far not recorded. It will 
be seen, therefore, that of the sixteen theoretical combinations of 
the four selected separate characters ten have been named, six of 
them falling under the canina group, the remaining four being 
dumetorum forms. These ten names do not exhaust the list of 
British roses which are classified under the canina-dumetorum 
series. Under R. lutetiana , for example, nearly a dozen named 
forms which may be distinguished according to size and colour of 
leaflet, shape of fruit, etc. are mentioned in Wolley-Dod’s 
“ List.” It is not improbable that these are important characters, 
perhaps more important than the presence or absence of glands on 
the leaves or peduncles, but the data regarding them is so in¬ 
complete for so many named varieties that it has been impossible 
to include them in the present analysis. In any case, the employ¬ 
ment of more than a few unit characters would lead to unnecessary 
complications. 
