F.C. Stern A Study of the Genus Paeonia

23. P.japonica (Makino) Miyabe & Takeda in Gard.Chron.,Ser.3,48,366, fig.153 (1910), et in Feddes Report. Sp Nov.12,319(1913); Makino& Nemoto, Nippon-Shokubutsu-Soran {Fl. Jap.), Ed. a, P.332 (1931) ; Komarov,Fl.U.R.S.S. 7, 27 (1937) ; F.C.Stem in Journ. Roy. Hort. Soc. 68,128 (1943). Syn. ? P.obovata var. glabra Makino in Journ. JaP.Bot. 5, No. 9, P.33 (1928); Makino & Nemoto, Nippon-Shokubutsu-So ran (Fl. Jap.), Ed. 2, P.332 (1931).P.obovata var. japonica Makino in Bot. Mag. Tokyo, 12, 302 (1898) ; Schipczinsky in Not.Syst. Herb. Hort. Bot. PetroP.2.45 (1921).

Description. Stem 30-37 cm. high (to 60 cm. fide Miyabe and Takeda), glabrous. Leaves 2 {fide Miyabe and Takeda) or 3, the lower two bitemate ; leaflets subsessile or the terminals borne on petiolules 9-14 mm. long ; blades elliptic or broadly elliptic, equally cuneate at the base and acute at the apex, or ovate from a wide-cuneate almost rounded base and acute at the apex (the lateral leaflets of the lateral sets of 3), the smallest laterals 3-3.4 cm. long, the rest 6-9 cm. long, 2.5-5 cm. wide, in fruit up to 12 cm. long and 5-8 cm. wide, green above, paler below, entirely glabrous. Flower 5-6 cm. across, subglobose and not much expanding. Petals strongly concave, obovate or orbicular-obovate, about 3-5 cm. long, white. Stamens 10-11 mm. long, filaments yellow, darker towards the base, anthers yellow. Carpels 3 or 4, narrowly conical, attenuated to the relatively large curved stigma, 16-17 mm. long, glabrous. Follicles about i -7 cm. long.

Distribution. japan : Hokkaido, Otaru, Faurie 3298 (K) ; Sapporo, Y. Tokubuchi (K.) ; Hondo, sine loc. Wilson, Am. Arb. Exped. 6666 (K) ; prov. Senano, Tschonoski (K).

The Japanese botanist Makino described P.japonica as a variety of P.obovata. Messrs. Miyabe and Takeda raised it to specific rank and named it P.japonica, distinguishing it from P.obovata by its white flowers, which open less widely than those of P.obovata because they have more concave petals and short stigmas. These authors also report that the leaves are glabrous. Some of the specimens from Japan, however, have scattered hairs on the underside of the leaves and these differ in no way from the leaves of P.obovata, as far as one can see from the dried specimens.

This plant proves to be a diploid while P.obovata and the var. Willmottiae are tetraploids. This makes it necessary to follow Messrs. Miyabe and Takeda and maintain this paeony as a species —P.japonica—although in its outward and visible characters it differs in only a small way from P.obovata ; the chromosome numbers, however, constitute the essential difference.

There is a herbarium sheet of a paeony from the mountains near Hakone, in Japan, at Kew, on which Dr. Stapf has written the name P.chaetocarpa. The plant looks like a form of P.japonica with tomentose carpels, but on close examination the carpels are not long and attenuated, which is a characteristic feature of P.japonica and all the Obovata grouP.It would not be surprising to find a variety of P.japonica with tomentose carpels as this variation is so often found among pairs of other herbaceous species. Since only one specimen of this possible species is known it is merely reported but not described as its status is uncertain.

P.japonica is said to be widely distributed in Japan as far north as the island of Yezo. It is not easy to raise from seed nor is it an easy plant to grow in the garden. [end page 78]