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Malvastrum coccineum
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* A genus first indicated by Nuttall under this name, which was subsequently changed to that of Nuttallia, but its diagnostic characters have not yet been given. Having been founded on exinvolucellate species, it was first only compared with Sida. But as involucellate species with the same habit became known, it was proposed by Hooker (Jour. Bot. 1. p. 196) to refer the latter to Malva and the former to Sida. As the radicle, however, proved to be inferior to all of them, they were all placed in the genus Malva in the Flora of North America (except an obscure species, the characters of which were not entirely understood); and a new genus was dedicated to Mr. Nuttall. A closer study of the American species thrown into Malva and Sida reveals characters which induce me not only to restore this genus, but to propose some other genera. The character which, on the whole, decides the question in favor of separating Callirhoë from Malva, namely the transverse process in the carpel, has indeed been already observed by Dr. Torrey (Fl. N. Amer. 1. p. 692) in a single species which I now refer to it; but it equally exists in the others, though much less conspicuously in some of them. The leading character of the genus which I propose to call Sidalcea, namely the double column separating into clusters of filaments, has already been noticed in the same work. The true Napæa, of Clayton, with dioecious flowers, a naked calyx, and an inferior radicle, is a totally distinct genus, which (in Man. Bot. North. United States, p. 69) I have already restored. There remain a set of ambiguous, perhaps all American, species, which have been referred to Sida when the involucel was inconspicuous, deciduous, or wanting, and to Malva when the involucel was manifest. From the latter, however, they differ by their capitate stigmas (a character which, though generally attributed to Malva, is found in no European species) and usually beaked fruit; and from Sida by the ascending ovule and inferior radicle. By separating these, under the name of Malvastrum (a name given by De Candolle to his division of Malva which comprises all the monospermous species, and which is no longer required now that the corresponding divisions are admitted genera), we leave both Malva and Sida much more natural and capable of exact definition. The genera in question would be characterised as follows.

Up: Transcriber's Preface
Malvastrum coccineum
Next: Malva