Vitex collium Sengun, 2024

Sengun, S., Ingrouille, M., Paton, A. & de Kok, R. P. J., 2024, Taxonomic revision of the Vitex trifolia complex (Lamiaceae), Blumea 69 (2), pp. 93-121 : 103-106

4. Vitex collium Sengun , sp. nov. — Fig. 7, 8; Map 4

This taxon differs from V. negundo L. in having lobed leaflet margins in which the tertiary venation continues to the apex of the lobe and the apex is often aristate and, very rarely and only its basal leaflets entire; as opposed to V. negundo that has a dentate margin with tertiary venation arching back before reaching the apex of the dentation and the apex acuminate and, frequently and any of the leaflets can be entire. In addition, it differs in its specific distribution that is in the frost prone regions of Central and Northern China as opposed to V. negundo occurring in Southern China as well as North India and Nepal. — Type: Sengun 53a (holo PE; iso K), China, Beijing.

Agnus-castus incisa (Lam.) Carrière var. multifida Carrière (1870 –1871) 416. — Vitex incisa Lam. var. multifida (Carrière) C.K.Schneid.(1911) 594. — Vitex negundo L. var. incisa (Lam.) C.B.Clarke f. multifida (Carrière) Reh- der (1917) 3481. — Vite x negundo L. var. heterophylla (Franch.) Rehder f. multifida (Carrière) Rehder (1947) 258. — Type: not indicated. Syn. nov.

Vitex incisa Lam. var. heterophylla Franch. (1883) 112. — Vitex negundo L. var. heterophylla (Franch.) Rehder (1947) 258. — Type: Herbier Drake del Castillo s.n. (holo P [P02888194]), ( China,) environs de Pékin.

Vitex negundo L. var. heterophylla (Franch.) Rehder f. albiflora H.W.Jen & Y.J.Chang (1991) 2. — Type: Jen 88654 (holo BFUH n.v.) , China, Beijing, Songshan. Syn. nov .

Vitex negundo L. var. sichuanensis J.L. Liu (1995) 501. — Type : J. L.Liu 505 (holo XIAS n.v.; iso PE [01477359]), ( China,) Sichuan, Xichang. Syn. nov .

Shrub or small tree, up to 2 m high. Bark smooth, grey. Leaves 5–7-foliolate; petiole 1.1–7.3 cm long. Leaflets: blades oblong-elliptic to narrowly elliptic, apex acuminate, base cuneate, margin lobed in which the tertiary venation continues to the apex of the lobe and often forms an aristate tip, rarely basal leaflet(s) entire, upper surface dark green, lower surface light green; secondary veins 3 –6 per side, slightly prominent, visible on both surfaces; terminal leaflets 2.3–13.4 by 1.1–4.8 cm; terminal petiolules 0.3–2.9 cm long; lateral leaflets 1.8–8.6 by 0.8–3.5 cm; lateral petiolules 0.1–1.7 cm long; basal leaflets 0.5–5.6 by 0.2–2.7 cm; basal petiolules 0–0.6 cm long. Inflorescence terminal, consisting of lateral cymes in dense clusters with persistent flowers; axis 8.5–14 cm long, smooth; bracteoles linear, up to (0.7–)1.4–3(–8.1) mm long, patent, persistent, drying black. Calyx glands absent to few; tube 1.1–2.1 mm long; lobes 0.5–1.1 by 0.3–1 mm, lobe apex sometimes acuminate but often aristate; flowering calyx 1.8–2.5 mm diam; fruiting calyx 2.7–3 mm diam, erect, covering most of the mature fruit. Corolla white or light purple to blue-violet; glands few or absent; tube 3.5–5.4 mm long; anterior lip orbicular, 2.7–5 by 2.9– 4.9 mm, apex rounded, anterior corolla lip with semi-circular area of hairs at the corolla mouth; lateral lobes 2.4–2.5 by 1.6–3 mm, apex round, patent; posterior lip: lobes 2.1–2.6 by 1.7–2.1 mm, apex round, reflected to erect. Stamens: filaments 3.2–4.8 mm long, slightly to strongly didynamous, inserted at half to lower 1/3 of the corolla tube; anther c. 1 mm long, pale brown to violet. Ovary c. 1 mm diam, glabrous, glands sometimes present; style 3.8–7.2 mm long; stigma lobes 0.4–1 mm long. Fruit when dried ellipsoid, 2.5–3.5 by 2–3 mm, apex truncate, glabrous.

Distribution — North China (Beijing Municipality, the provinces of Hebei and Shanxi, an isolated population in Luding County in Sichuan Province).

Habitat & Ecology — Pine forests and mixed thickets on mountain slopes in frost prone regions at 160–1800 m altitude. Flowering and fruiting: August.

Vernacular name — Jing tiao (Chinese).

Conservation status — IUCN assessment gives the ex- tent of occurrence (EOO) as greater than the threshold for a threatened category, thus the status would be least concern (LC) but the area of occurrence (AOO), meets the threshold for the Endangered (E) category. Unfortunately, we have found no data on the threats facing the localities or on the status of the populations. Therefore, we have categorised this species as Data Deficient (DD).

Note — This taxon has never been recognised at species level before. It has been named here V. collium Sengun for it translates to English as the ‘ Vitex of the hills’ in recognition of its native habitat in the hills of China.

Figures

Map 4 Natural distribution of Vitex collium Sengun.