> 
378 RypBERG: NOTES ON ROSACEAE 
evince these characters have other marks more obvious. Their 
roots are annual, or now and then of biennial duration. All other 
plants that ever were referred to Pofentilla are perennial, and 
very many suffrutescent.’’ So far, Dr. Greene. Let us see of 
what value these characters are. Potentilla nivea, P. grandiflora, 
and P. subacaulis, also trifoliolate species of the Linnaean Poten- 
tilla, and hence part of Tridophyllum Necker, do not fulfill this 
characterization. Some may claim that they did not constitute 
a part of Necker’s genus, but why not? Necker placed the pinnate- 
leaved species in Potentilla, the trifoliolate ones in Tridophyllum, 
and the digitate-leaved ones with more than three leaflets he 
transferred to Tormentilla. Ina note under Tormentilla he states 
that 5 species of Potentilla are to be referred to Tridophyllum; 
hence the five given above, of which P. subacaulis has very long 
styles and the other two have rather large achenes. They are all 
thrée perennials. 
But is Tridophyllum as modified by Greene a well-defined 
genus? Potentilla intermedia and P. heterosepala have both the 
very short styles and numerous small achenes, and are both in- 
cluded in the SUPINAE group by Dr. Wolf, the world-authority 
on Potentilla; but they are both perennials. The former is very 
close in habit to P. monspeliensis, which occasionally is a short- 
lived perennial. Potentilla Newberryi has all the character of 
that group, but the style is long. The short style, often glandular 
at the base, and the numerous small achenes, characteristic of the 
SUPINAE group, are found in many other Potentillas, especially 
of the MULTIFIDAE group. These characters are worth little as 
generic characters. 
While vol. 25, part 4, of the North American Flora was going 
through the press, we received at the New York Botanical Garden 
the excellent monograph of the genus Potentilla by Dr. Theodor 
Wolf.* If this valuable work had reached us a little earlier, some 
changes and corrections might have been made in my monograph, 
and quite a number of synonyms could have been added. The 
monographing of the whole genus, for the whole world, is a stu- 
pendous undertaking. Dr. Wolf’s work is one of the most elab- 
orate, conscientious, and critical ever published. It is a large 
*Bibliotheca Botanica, Heft 71. y 
