F.C. Stern A Study of the Genus Paeonia

Section Onaepia

brownii group.—P.Brownii and P.californica are the only paeony species found on the American continent and constitute a distinct section of the genus. This section, named by Lindley ONAEPIA, is separated from the section PAEON, which also comprises herbaceous paeonies, by the petals which are not longer or only slightly longer than the sepals and by the disc which is produced as fleshy lobes at the base of the carpels, also by the seed, which is cylindrical ovoid.

The other species -which have these prominent discs are the shrubby paeonies of China which belong to the section MOUTAN. The small petals of these American species are somewhat like the small petals of some of the forms of the shrubby paeony P.Potanini with particularly small [end page 19] flowers. Stebbins (1938) refers to this connection between the herbaceous paeonies of North America and the shrubby paeonies of western China. All the species of both these groups are diploids. Stebbins writes : " The line which gave rise to P.californica and P.Brownii must have branched off from the rest of the genus very Early in its history. The fact that the closest connection between the Old and the New World species of paeonia is through species endemic to such remote( and different regions as southern California and south-western China suggests that this connection is very ancient."

Stebbins, who has studied these species very carefully, contends that the two paeonies of North America should be considered separate species. This is the conclusion come to in this study, and is discussed under P.Brownii on page 51. He draws attention to the unusual range of the two paeonies ; P.Brownii being found from the north of the State of Washington southwards to northern California, and P.californica in central and southern California, the northern species [end page 20] growing at an altitude of 3,000 to 6,000 ft. and the southern from sea level to 4000 ft. There is no doubt that these paeonies are closely allied to each other and it is an interesting speculation to consider how these two paeonies came to inhabit this corner of the American continent.Maps a-z