Lasianthus pierrei Pit. (1924: 386)

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

56. Lasianthus pierrei Pit. (1924: 386) — Fig. 85 (plate), Fig. 84 (map)

Type: — VIETNAM. Ba Ria— Vung Tau , Con Dao District, October 1876, Harmand 6174 (holotype P! [P03981118]; isotype P! [P03981115]) .

Specimens examined: — VIETNAM. Central: Khanh Hoa Province, Hon Ba Nature Reserve, 900 m elev., 24 July 2018, Dang V.S. & Hoang N.T.B.N., Dang 195 ( VNM); in the same location, 1502 m elev., 15 June 2019, Dang V.S. & Hoang N.T.B.N., Dang 345 ( VNM, the herbarium of Iriomote Station (Japan )) .

Distribution: —Endemic to Vietnam (currently known as Con Dao National Park in Con Dao District of Ba Ria—Vung Tau Province and Hon Ba Nature Reserve of Khanh Hoa Province).

Habitat & Ecology: —Growing under the shade of evergreen forest or on a hill of the forest at 500–1600 m elev.

Phenology: —Flowering and fruiting from June to November.

Vernacular name: —Xú hưƠng pierre.

Notes: — Lasianthus pierrei was described in 1924 from a Vietnamese specimen (A. Harmand 6174). It is characterized in the field as having yellow-brown pubescent branches, linear-lanceolate leaves, secondary veins 4–6 on each side of midrib; petioles 4–5 mm long, flowers white, calyx tube longer than the lobes, and fruits globose with 4 pyrenes.

Additional fruit morphology for L. pierrei: Fruit drupaceous, globose, 5–7 mm long, 4–5 mm in diam., sparsely strigose, crowned by persistent short calyx lobes; pyrenes 4. Seeds ovoid, 3–4 mm long, sulcate on the abaxial face, brown when dry.

Figures

FIGURE 84. Distribution maps of Lasianthus phamhoangii, L. pierrei, L. repoeuensis and L. rhinocerotis subsp. pedunculatus.

FIGURE 85. Lasianthus pierrei Pit. (from Dang 345, VNM and the herbarium of Iriomote Station (Japan)): A. Branch, B. Stipules, C. Abaxial leaf surfaces, D–E. Inflorescence showing side view calyx, buds and flower, F–G. Young fruits.