Family LAMIACEAE
Genus Isodon
Species Epithet longitubus
Author of Basionym Miq.
Author Kudo
Infrasp. rank
Infraspecific Name
Author of Basionym
Author
Reference Labiat. Sino-Jap. Prodr.: 139 (1929).
Synonym Plectranthus longitubus Miq. in Ann. Mus. Bot. Lugd.-Bat. 2: 102 (1865). Plectranthus longitubus Miq. var. contractus Maxim. in Bull. Acad. Sci. St.-P{e'}t. 20: 450 (1875). Amethystanthus longitubus (Miq.) Nakai in Bot. Mag. Tokyo 48: 790 (1934). Rabdosia longituba (Miq.) Hara in J. Jap. Bot. 47: 197 (1972).
Japanese Name Aki-ch{o~]ji.
Kana Name アキチョオジ.
Description Perennial herbs. Rhizomes woody, creeping, branched. Stems erect, 70--100 cm tall, 4-angled, recurved puberulent. Leaves opposite, membranaceous; petiole 0.5--3 cm long, sparsely pubescent; blade ovate, oblong-ovate or widely lanceolate, 7--12 cm long, 2.5--4 cm wide, apex acuminate, base acute or cuneate, decurrent into petiole, acute-serrate, upper surface sparsely pubescent, lower surface glabrous except pubescent nerves. Flowers August to October. Inflorescences terminal and in upper leaf axils, raceme-like paniculate, 10--20 cm long; rachis subdensely puberulent. Bracts lower ones leaf-like, small, gradually smaller upward. Bracteoles setaceous 1--2 mm long. Peduncle 3--10 mm long, pedicel 2--5 mm long, minutely puberulent. Calyx campanulate, bilabiate, ca. 3 mm long in flower, 6 mm long in fruit, minutely puberulent; upper lip 3-lobed, lobes deltoid-ovate, acuminate; lower lip slightly longer than upper lip, 2-lobed, lobes narrowly triangular-ovate, attenuate-acuminate. Corolla bilabiate, blue, 17--20 mm long, short pilose outside, 12--14 mm long, slightly gibbous on upper side at base; upper lip 2--3 mm long, shallowly 4-lobed; lower lip 3--4 mm long, slightly longer than upper lip. Stamens 4, didynamous, included. Nutlets globose, ca. 1.5 mm long, smooth, glabrous.
Chromosome Number
Distribution in Japan C. to W. Honshu (westward from Gifu Pref.), Shikoku and Kyushu.
Habitat Sunny, moderately moist meadows; 100--1700 m.
Distr. in the World Endemic to Japan.
Icon Kitamura et al., Herb. Pl. 1: t. 50 403; Satake et al., Herb. Pl. 3: photo. 64 1 & 2, as Rabdosia longituba; Inami, Ill. Pl. Hiroshima 2: t. 81, as Plectlanthus longitubus; Makino, rev. ed.: t. 2627.
Note This species has been reported from C. China (Fl. Reipubl. Pop. Sin. 66: 442, 1977). Based on the description, however, the Chinese plants appears to be a different species. The white flowered form has been named f. albiflorus (Makino) Hara (Enum. Sperm. Jap. 1: 208, 1948).
Annotator G. Murata and T. Yamazaki