Isodon hispidus (Benth.) Murata

Suddee, S., A. J. Paton, & Parnell, J. (2004). A Taxonomic Revision of Tribe Ocimeae Dumort. (Lamiaceae) in Continental South East Asia I. Introduction, Hyptidinae & Hanceolinae. Kew Bulletin, 59(3), 337-378. doi:10.2307/4110949

Distribution

Himalaya, India, Burma, Laos & Thailand.

Ecology

In pine forest or hill evergreen forest; 700 - 2200 m.

Morphology General Habit

Erect perennial herb or undershrub up to 2 m tall

Morphology Leaves

Leaves chartaceous, broadly ovate, 30 - 60 x 20 - 45 mm, apex acute, margin serrate or serrate-crenate, base rounded or subtruncate, puberulous to pubescent above, tomentose or villous and dotted with minute sessile glands beneath, venation subprominent to prominent beneath; petioles up to 40 mm long in lower leaves, gradually reduced in length with leaves becoming sessile above, tomentose or villous

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens long-exserted; anterior pair inserted above the middle of corolla tube, glabrous or sparsely villous at base; posterior pair inserted near the base of corolla tube, villous at base

Morphology Reproductive morphology Flowers Calyx

Calyx campanulate, 1.5 - 2 mm at anthesis, uniformly densely pubescent or densely villous, tubular-campanulate, 4- 5 mm long in fruit, inconspicuously 2-lipped; teeth subequal, lanceolate, usually acuminate at apex; tube declinate, 10-nerved, twice as long as teeth, glabrescent, with sessile glands outside, not gibbous at anterior base

Morphology Reproductive morphology Flowers Corolla

Corolla white, straight, 4- 7 mm long; posterior lip subequally 4- lobed, lobes rounded or obtuse at apex, pubescent, with sessile glands on back; anterior lip orbicular, 2 - 2.5 mm long, subequal to posterior, slightly concave, glabrous inside, glabrescent to pubescent, with sessile glands outside; tube 3 - 4.5 mm long, subtubular, slightly dilated at throat, glabrous or slightly pubescent, without sessile glands outside

Morphology Reproductive morphology Flowers Disc

Disc annular with equal lobes

Morphology Reproductive morphology Flowers Gynoecium Style

Style long-exserted but shorter than stamens

Morphology Reproductive morphology Fruits

Nutlets brown, ellipsoid or oblong, 1 - 1.5 mm long, smooth, producing mucilage when wet or not.

Morphology Reproductive morphology Inflorescences

Inflorescence terminal and axillary, composed of several lax, narrow raceme branches, forming a panicle, pubescent to tomentose on axis; cymes with peduncle up to 25 mm long, lax or dense, 8 - 15-flowered; bracts ovate or ovate- lanceolate, adaxially glabrescent, pubescent or sparsely villous, abaxially densely villous; bracteoles linear, linear-oblong or linear-oblanceolate, 1 - 2 mm long, villous, caducous or persistent; pedicels 1 - 3 mm long at anthesis, 3 - 10 mm long in fruit, sparsely villous

Morphology Stem

Stems woody at base, branched or not, quadrangular, pubescent to tomentose, sometimes densely villous

Note

This species is very similar to Isodon lophanthoides, and the two species are often confused in herbaria. In the wild, I. hispidus is a larger and more pubescent taxon, although the types (Wall. Cat. 2741) are less hairy than some specimens. Li (1988) reduced Rabdosia shimizuana Murata to a synonym of Isodon hispidus stating that it is identical to I. hispidus according to Murata's description. However, from the photograph of the holotype R. shimizuana has the leaves congested near the stem base, and therefore resembles several specimens of I. lophanthoides from various parts of Thailand and Indo-China. It is clear that R. shimizuana is actually just a form of I. lophanthoides, which Muschler (1907) recognised as P. volkensianus Musch. and Doan (1936) recognised as P. striatus var. kerrii Doan (nom. inval.).

Phenology

Flowering September - December, fruiting November -January.

Type

India, Sillet, [Sylhet, in Bangladesh] Wallich s.n. [syntype K!]; India, Sillet [Sylhet], Nov. 1829, De Silva in Wall. Cat. 2741 [syntype K!, K-W!].

Vernacular

Thai: A-to Chu Na Tsuh (Lisu).