Vitex trifolia

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 : 94-95

Vitex trifolia complex

Vitex L. sect. Euagnus subsect. Paniculatae Schauer (1847) 683, comb. illeg. — Vitex L. sect. Euagnus subsect. Terminales Briq. (1895) 172, nom. superfl. — Type: Vitex agnus-castus L.

Agnus -castus Carrière (1870 –1871) 415. — Vitex L. sect. Agnus -castus (Carrière) Briq. (1895) 172. — Lectotype (designated here): Agnus-castus vulgaris Carrière (= Vitex agnus-castus L.).

Shrubs or small trees. Leaves opposite, (1–)3–5(–7)-foliolate; leaflets: venation pinnate, glabrous above or with only hairs on the veins, velutinous below; hairs whitish, occasionally purple in V. trifolia and V. hybrida , appressed, with a powdery exudate on apical cell, sessile glands absent; petiolules round in cross-section, with minutely curled hairs. Inflorescence an indeterminate thyrse consisting of lateral cymes in lax or dense clusters, terminal or axillary; axis square in cross-section, appressed pubescent; bracts usually 1-foliolate; bracteoles ovate to linear, appressed or patent, persistent or caducous, velutinous. Calyx erect in flower, patent to erect in fruit, 5-lobed, zygomorphic; calyx tube 5-ribbed; lobes clearly developed, ac- crescent, persistent, velutinous; glands absent to many. Corolla 5-lobed, lobes basally fused up to 10 % of length, margin entire, covered outside with appressed hairs; anterior lip orbicular to ovate or spathulate, apex round to acute, reflexed, two clear ridges and a semi-circular area of hairs at the corolla mouth (except in V. agnus-castus ); lateral lobes erect or patent, apex rounded; posterior lip 2-lobed, erect or reflexed, apex acute or rounded. Stamens: filaments slightly didynamous, with anterior pair longer to equal than posterior pair, with a tuft of erect simple multicellular hairs at base, otherwise glabrous except in some V. pseudonegundo in which occasional hairs along the filament, inserted half to 1/3 of the way on the corolla tube, clearly exceeding the corolla tube; anthers beige to purple, thecae mostly parallel, occasionally divergent. Ovary globose, glabrous (except in V. pseudonegundo ), glands few to many; style glabrous; stigma 2-lobed. Fruit drupaceous, 4-seeded, broadly obovoid to globose or ellipsoid, glabrous except in V. pseudonegundo , smooth, glaucous.

Distribution — The species of the complex are distributed from the Mediterranean, east to Japan and Hawaii and south to northern Australia and the Pacific.

Notes — 1. The V. trifolia complex was first defined by De Kok (2007) based on the species’ unique hair type. It then only included the species V. agnus-castus , V. benthamiana , V. negundo s.lat., V. pseudonegundo and V. trifolia s.lat. This is expanded here to nine species, to include V. bicolor , V. collium , V. hybrida and V. rotundifolia . However, at this point in time, it would not be appropriate to formally recognise the V. trifolia complex as a section within Vitex . This is because it would require the complex being defined against other groups within the genus; however, not enough is known about the rest of the genus to do so.

2. Within the genus Vitex , section Euagnus was illegitimately described by Schauer (1847: 683) as having an erect corolla upper lip and a calyx that is bell-shaped with a short tube and with five lobes. Within this section, the species of the V. trifolia complex were part of a subsection Paniculatae Schauer. This subsection was based on the character of an inflorescence consisting of panicles with terminal cymes. The type of this group was V. agnus-castus and the rest of the species included were V. alata B.Heyne , V. altissima L.f., V. bahiensis Schauer , V. bicolor , V. heterophylla Roxb. , V. incisa Lam. , V. loureirii Wight ex C.B.Clarke , V. negundo , V. peduncularis Wall. ex Schauer , V. pubescens Vahl , V. punctata Schauer , V. timoriensis Walp. , V. trifolia and V. umbrosa Sw.

3. Carrière (1870 –1871) described a genus ( Agnus -castus Carrière) based on a series of species, which are now con- sidered to be synonyms of V. agnus-castus , V. collium and V. negundo . In 1895, Briquet (1895: 172) changed it to section Agnus -castus. He also changed the name of Schauer’s subsection Paniculatae to Terminales Briq., a superfluous name. He kept the type species V. agnus-castus , but included a smaller number of species, namely, V. alata , V. altissima , V. bahiensis , V. limonifolia Wall. and V. trifolia .