Lasianthus eberhardtii Pit. (1924: 375)

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

19. Lasianthus eberhardtii Pit. (1924: 375) — Fig. 39 (plate), Fig. 37 (map)

Type: — VIETNAM. Bac Kan Province, Ban Khuang, Eberhardt 4646 (holotype P! [P02285249]; isotypes P! [P02285249, P02285249]) .

Specimens examined: — VIETNAM. Northern: Lao Cai Province, Hoang Lien National Park , 870 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 4669? ( DLU, FU) . Central: Thanh Hoa Province, Thuong Xuan , 17 June 2016, Trinh N.B. TH16-10 ( VAFS) ;

Distribution: —Endemic to Vietnam (currently known as Bac Kan, Lao Cai, Thai Nguyen, and Thanh Hoa).

Habitat & Ecology: —Growing in open shade, on less sandy ground in primary or secondary forest at 700–1500 m elev.

Phenology: —Flowering and fruiting from June to November.

Vernacular name: —Xú hưƠng eberhardt.

Notes: — Lasianthus eberhardtii was described in 1924 from a Vietnamese specimen (Eberhardt 4646). This species can easily be recognized in the field in having yellow hirsute branches, oblong leaf blade, tip pointed 12–15 mm long, secondary veins 9–12 on each side of midrib, bracts 10–20 mm long, and fruits 4 mm long, pyrenes 6.

Lasianthus eberhardtii is closely related to L. harmandianus Pierre ex Pit. (1924: 376) which is endemic to Laos, but differs from the latter by having leaves long hairy along margin (vs. smooth margin), bracts 10–20 mm long (vs. 6.5 mm long), flowers grouped by 1–4 (vs. 8–12) and calyx 6, erect (vs. 5, reflexed).

Figures

FIGURE 37. Distribution maps of Lasianthus dalatensis, L. dienkhanhensis, L. eberhartii and L. elevatineurus.

FIGURE 39. Lasianthus eberhardtii Pit. (A–D & H–I from TH16-10 and E–G from Eberhardt 4646, VAFS and P): A. Habit, B. Branch, C. Close-up of young branch and leaves, D. Stipules, E. Abaxial leaf surfaces, F–G. Inflorescence showing side view flowers and bracts, H–I. Young fruits (A–D & H–I: photos by Trinh Ngoc Bon).