POTENTILLA LEM MONI (Wats.) Greene, Pittonia, i : 104, 1887.
Ivesia Lemmoni Wats. Proc. Am. Acad. 20 : 365. I 885.
This species should, I think, be placed as an appendix to this group. It has no relationship to any of the Ivesias, and is a true Potentilla in every respect, except as to the number of pistils, which are only half a dozen or so. Its nearest relative is, without doubt, Potentilla erinila, from which it differs by the longer, nar rower and fewer leaflets, the sparser pubescence, the few pistils and the longer hairs on the receptacle.
(zraciles. This group is the most difficult in the whole genus. It contains so many and perplexing forms, that I have not yet come to any definite conclusion as to how to treat it. Watson united all except the first (partly) and the last into one species. This is far from satisfactory. It would have been much more logical to make P. effusa a variety of P. Hippiana, P. Breweri one of P. Plattensis, or P. eniarginata one of P. fragifonnis than to include P. Nuttallii and P. fiabelliformis in P. gnzeilis. The group contains not less
than ten well marked American forms and about half a dozen less marked ones. Of these ten forms all except one have been recog nized at one time or another as species or varieties, and as far as I know, all but two have received names. I shall temporarily re gard these ten as species.
This view I dare to express, as I have had chance to study this group especially in the field. I have collected the following myself: P. pulelzen'inza, Blasclikeana, flabellifornlis, var. etenopliora, fastigiata, etomentosa. and Nuttallii. I have seen the following grow ing together: puickerrimez and Nuttallii, Blaschkeana and Nuttallii, Blase/IA-calla and fiabeWormis, Blaselikeana and aenophora,flabelli_ forms and Nuttallii. In no case have I found intermediate forms. In the herbaria that I have looked over I have found one specimen between Blasclzkeana and aenophora, a few between Nuttallii and Blasekkeana or fastigiata, etc., but as a rule they can be distinguished fairly well.