Cypripedium japonicum Thunberg, Fl. Japon. 30 (1784) et Ic. Plant. Japon. t. 1 (1794); a C. formosano Hayata caule et ovario magis pilosis, petalorum colore, labelli forma, ab aliis speciebus generis foliorum nervis flabellatim divergentibus margine ut videtur terminantibus distinguendum.-Blume, Orchid. Archip. Ind. & Japon. 169, t.59, fig. 3, 1-5 (1858); Van Houtte in Fl. des Serres, Ser. 2, XX. 35, t.2064-2065 (1874); Gard. Chron. N. Ser. III. 624, fig. 129 (1875); T. Moore in Florist, 1875, p. 220, cum ic.; Floral Mag. N. Ser. 1875, t.171; Franchet & Savatier, Enum. Pl. Japon. II. 40 (1876); Godefroy-Lebeuf in L'Orchidophile, 1887, p. 176, tab. fig. 3; Pucci, Cyprip. 124 (1891); Stein, Orchideenbuch, 177, fig. 60 (1892); Franchet in Morot, Journ. de Bot. VIII. 234 (1894); Rolfe in Orch. Rev. IV. 334 (1896); Kraenzlin, Gen. & Sp. Orch. I. 31 (1897); Desbois, Cyprip. etc., 33 (1898); Finet in Bull. Soc. Bot. France, XLVII. 285 (1900) et in Rev. G n. Bot. XIII. 501, t.12, fig. 39-41 (1901); Mallet in Gard. Chron. Ser. 3, XXXIII. 356, fig. 138 (1903); Pfitzer in Engler, Pflanzenreich, Orch.-Pleonandr. 42, fig. 5B, 6B (1903); Forbes & Hemsley, Index Fl. Sinen. (in Journ. Linn. Soc. London, Bot. XXXVI.) III. 65 (1903); Orch. Rev. XII. 119 (1904), XXIV. 175, 176 (1916), XXXVI. 64 (1928), XXXIX. 167, 182 (1931), XLIV. 184, tab. p. 179 (1936); Matsumura, Index Pl. Japon. II. 241 (1905); Somoku Dzusetsu, Ed. 3, XVIII. t.84 (1912); Schlechter, Orchideen, 26 (1915) et in Fedde, Repert. Nov. Spec. Beih. IV. 82 (1919); Arnold in Orch. Rev. XXXV. 176 (1927); Darnell, Orchids for the Outdoor Garden, 102 (1930); Gard. Chron. Ser. 3, LXXXIX. 361 (1931); Journ. Roy. Hort. Soc. London, LVII. Proc. p. xxxix (1932); Darnell in Gard. Chron. Ser. 3, CII. 447, fig. 195 (1937). Cypripedium japonicum was described by Thunberg in his Flora of Japan so long ago as 1784, but nearly a hundred years elapsed before cultivated specimens were seen in England. Since then the species has only been spasmodically in cultivation owing to the difficulties of importation and culture. The species may be distinguished from all other species, except its near ally C. formosanum Hayata, by the possession at the middle of the stem of two large fan- shaped leaves, the nerves of which diverge from one another and apparently terminate at the margin, though they are actually joined by a quite obscure marginal vein. C. formosanum has the same general vegetative features but the scape is nearly glabrous, the ovary is only slightly hairy and the lip is rather different in shape. C. japonicum occurs in the southern peninsula of the island of Yezo and in the north-eastern half of Hondo, the largest island of the Japanese archipelago. It was formerly.