Lasianthus lucidus Blume (1826: 997)

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

47. Lasianthus lucidus Blume (1826: 997) — Fig. 74 (plate), Fig. 73 (map)

Type: — INDONESIA. Java, Blume s.n. (lectotype L! [L0000697], designated by Zhu 2002) .

Mephitidia lucida DC. (1830: 453) . Type: — INDONESIA. Java, Blume s.n. (lectotype L! [L0000697], designated by Zhu 2002).

Specimens examined: — VIETNAM. Northern: Ninh Binh Province, 21 August 1889, Bon 4214 ( HN, P) . Central: Thua Thien Hue Province, Bach Ma National Park, 1193 m elev., 26 July 2019, Dang V.S. & Naiki A., Dang 405 & Dang 416 ( VNM, the herbarium of Iriomote Station (Japan)); Da Nang City, Ba Na Nature Reserve , 1489 m elev., 27 July 2019, Dang V.S. & Naiki A., Dang 423 ( VNM, the herbarium of Iriomote Station (Japan )) .

Distribution: —Widespread in tropical and subtropical regions in Asia ( Bangladesh, China, India, Indonesia, Malaysia, Myanmar, New Guinea, Philippines, Thailand). In Vietnam, Lasianthus lucidus occurs in Da Nang, Ha Nam, Nam Dinh, Ninh Binh and Thua Thien Hue.

Habitat & Ecology: —Growing in the shade of evergreen forest or the hill of the natural forest at 700–1500 m elev. The species was collected from the understory of a forest dominated by Lasianthus japonicus Miq. (1867: 110) , L. fordii Hance (1885: 324) , Phyllanthus sp. , Croton persimilis Müll.Arg. (1865: 116) , Streblus asper Lour. (1790: 615) , Litsea globosa Kosterm. (1970: 99) , Markhamia stipulata Seem. (1863: 226) , Cinnamomum balansae Lecomte (1913: 75) .

Phenology: —Flowering and fruiting from July to January of the next year.

Vernacular name: —Xú hưƠng suốt.

Notes: — Lasianthus lucidus is easily identified in the field in having ovate to ovate-elliptic leaves, secondary veins 3–5 on each side of midrib, calyx widely campanulate and lobes 5, and fruits globose to ovoid, blue when ripe. Lasianthus lucidus is similar to L. fordii Hance (1885: 324) but differs by having smaller leaves (4–9 × 1.5–3 cm vs. 6–10 × 3–5 cm), leaf blade membranaceous (vs. chartaceous) and calyx lobes longer (vs. shorter) than calyx tube.

Figures

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

FIGURE 74. Lasianthus lucidus Blume (A–D & G–H from Dang 405 and E–F & I–J from Dang 416, VNM and the herbarium of Iriomote Station (Japan)): A. Branch with fruits, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E–F. Inflorescence showing side view flower buds, G. Flower bud and fruits, H–J. Young and mature fruits.