Lasianthus micranthus Hook.f. (1880: 190)

Dang, Van-Son & Naiki, Akiyo, 2023, A revision of the genus Lasianthus Jack (Rubiaceae) from Vietnam, Phytotaxa 581 (1), pp. 1921-1935 : 1921-1935

48. Lasianthus micranthus Hook.f. (1880: 190) — Fig. 75 (plate), Fig. 73 (map)

Type: — INDIA. Bengal , Mishmi hills, Griffith 2930 (holotype K!, [K000031633]) .

Litosanthes micrantha (Hook.f.) Deb & M.Gangop. (1989: 220) .

Lasianthus balansae (Drake) Pit. (1924: 396) ; Mephitidia balansae Drake (1924: 396) . Type:— VIETNAM. Ha Noi City, Ba Vi District , 500 m elev., November 1887, Balansa 2652 (lectotype K! [K000777016], designated by Napiroon et al. 2020).

Specimens examined: — VIETNAM. Northern: Lang Son Province, Cao Loc District, Dong Dang Commune, 10 February 1886, Balansa 659 (P); Lao Cai Province, Hoang Lien National Park , 850 m elev., 29 April 2016, Naiki A., Yahara T., Toyama H., Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S. V 4640 ( DLU, FU, VNM, the herbarium of Iriomote Station ( Japan)); Vinh Phuc Province, Tam Dao National Park, 1124 m elev., 13 November 2018, Dang V.S. & Naiki A., Dang 238, Dang 239 & Dang 260 ( VNM, the herbarium of Iriomote Station ( Japan)); Ha Noi City, Ba Vi National Park , 1267 m elev., 17 November 2018, Dang V.S. & Naiki A., Dang 273 & Dang 279 ( VNM, the herbarium of Iriomote Station ( Japan)) .

Distribution: —Widespread in tropical and subtropical regions in Asia ( China, India, Thailand). In Vietnam, Lasianthus micranthus occurs in Lao Cai, Lang Son, Ha Noi, and Vinh Phuc.

Habitat & Ecology: —Growing in the shade of the evergreen forest and the hill of natural forest at 800–1300 m elev.

Phenology: —Flowering and fruiting from October to April of the next year.

Vernacular name: —Xú hưƠng balansa.

Notes: —A Vietnamese species, L. balansae (Drake) Pit. (1924: 396) was treated as the synonym of L. micranthus by Zhu and Taylor (2011).

Lasianthus micranthus is easily recognizable in the field in having sparsely puberulent to glabrous branches; ovate, ovate-oblong to oblong-lanceolate leaves, secondary veins 5–6 on each side of midrib, calyx lobes 5, and fruits globose, blue when ripe.

Figures

FIGURE 73. Distribution maps of Lasianthus longissimus, L. lucidus, L. micranthus and L. naikii.

FIGURE 75. Lasianthus micranthus Hook.f. (A–D from Dang 273 and E–J from Dang 260, VNM and the herbarium of Iriomote Station (Japan)): A. Branch with flowers and fruits, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E–G. Inflorescence showing side view buds and flower, H. Young fruit, I–J. Mature fruits.