A Monograph of the Genus Rosa in North America. II. R. foliolosa

Abstract

The study of Rosa foliolosa Nutt. is discussed under the disciplines of gross- and micro-morphology, phytogeography, cytology, and taxonomy. Rosa foliolosa Nutt. is a remarkably distinct species within the sec- tion Cinnamomeae and the subgenus Eurosa (Lewis 1957). First pub- lished by Torrey and Gray (1840) from a manuscript by Nuttall, the species is described with: branches slender, glabrous, armed with very weak scattered deciduous bristly prickles, and sometimes with persistent short and nearly straight stipular prickles; leaflets 7-11, linear-oblong, glabrous, shining above, sharply serrate, crowded, the lower pair close to the narrow glandular-ciliate stipules; the petiole midrib often setose and pubescent; mostly solitary and almost sessile; calyx glandular-hispid; the segments reflexed, often with lateral appendages; fruit subglobose, somewhat hispid. To Nuttall's description, Torrey and Gray added several phrases of questionable validity. One especially have created a minor intraspe- cific problem, i.e., their flowers small, apparently rose-color. The rose coloured petals have been considered typical of R. foliolosa and this quite naturally has led to the naming of the white petalled indi- viduals as var. alba Bridwell and as f. alba (Bridwell) Rehder. From the holotype collected on the 'Arkansana plains' and now housed in the Gray Herbarium, it is impossible to determine if rose or white petals were a part of the Nuttall collection. It is of interest, however, that white petalled individuals occur (as observed in Texas by Dr. L. H. Shinners and myself) more frequently than do the pink, although extremely light pink to rose colours may be discerned (especially in Oklahoma). Certainly the occurrence of white is not as a result of an 1 All techniques and methods used in this study are similar to those described for the monographic treatment of Rosa acicularis Lindl (Lewis 1959).