9. Epilobium amurense subsp. laetum (Wall. ex Hausskn.) Raven, Bull. Brit. Mus. (Nat. Hist.) Bot. 2: 367. 1962; Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 505. 1972.
Peter C. Hoch and Peter H. Raven
Epilobium laetum Wall., Numer. List 216, n. 6329. 1832, nom. nud., quoad A. Epilobium laetum Wall. ex Hausskn., Monogr. Epil. 218. 1884; H. LJv., Ic. Gen. Epil. t. 97. 1910. Epilobium nepalense Hausskn., Oesterr. Bot. Zeitschr. 29: 53. 1879; Monogr. Epil. 218. 1884. Lectotype: Nepal, without definite locality, Wallich s.n. (C). Epilobium teragonum sensu Clarke in Hook. f., Fl. Brit. Ind. 2: 586. 1879, pro parte, non L.
Ascending perennial herb, forming basal rosettes or short leafy soboles; stems 15-50 cm tall, simple or sparsely branched, the raised lines decurrent from the margins of the petioles markedly strigillose, sparse to dense strigillose pubescent, with glandular hairs mixed on the inflorescence. Leaves narrow elliptic to narrow ovate, the lower ones obovate, 2.5-7 x 1.2-3 cm, denticulate to sharply serrate, sparsely strigillose, subacute, the base cuneate to petiole 3-6 mm long. Inflorescence erect, dense strigillose. Ovaries 3.2-4 cm, pedicels 0.5-0.9 cm. Sepals 3.5-5 mm long, sparse to dense strigillose. Petals 5-7.5 mm long, white, notched. Style 3-4 mm long. Stigma capitate to short clavate, surrounded by the anthers before anthesis. Capsules 5-7.5 cm long, strigillose, pedicels 1-1.5 cm long. Seeds 0.8-1.1 x 0.38-0.42 mm, coarsely papillose, with virtually no visible chalazal collar; coma 4-6 mm long, dingy white, easily detaching.
Type: Towards Gosainthan, Nepal, July 1821, Wallich 6329A (BM in part; G; K, isotypes).
Distribution: Hunza and Kashmir to Yunnan, Sichuan and Hubei; subsp. amurense continues to Japan and Siberia.
Raven (1962) adopted a broad view of E. amurense as a highly variable species widespread in eastern Asia, and treated white-flowered populations from the Himalayan region as subsp. laetum, a treatment followed by subsequent authors in this region. Subsequently, Raven (1977) in his treatment for the Flora of Taiwan dropped the subspecific recognition and treated all specimens of this affinity as E. amurense. This species is in need of critical study, including specimens from China, Japan,, and the Soviet Union, and in anticipation of that work it seems advisable to maintain subsp. laetum for plants in the Himalayan region. As noted by Raven (1962), this species has coarsely papillose seeds. Fl. Per.: Jul-Aug. Fr. Per.: Jul-Sep.