Osmanthus heterophyllus (G.Don) Green (1958: 508)

Diep, Tran Thi Ngoc, Doan, Ha Thi Thanh, Quang, Bui Hong, Averyanov, Leonid V., Lyskov, Dmitry F., Samigullin, Tahir H., Sennikov, Alexander N. & Nuraliev, Maxim S., 2025, An overview of the genus Osmanthus (Oleaceae) in Vietnam, with two new records and lectotypifications, Phytotaxa 684 (1), pp. 33-54 : 40-43

2. Osmanthus heterophyllus (G.Don) Green (1958: 508) ( Figs. 4 , 5 )

References: — Lu (1992: 96, Pl. 27 Fig. 1 ), Yamazaki (1993: 130), Chang et al. (1996: 288, Fig. 245 (1, 2)), Yang & Lu (1998: 141), Xiang & Ji (2004: 51).

Basionym: — Ilex heterophylla Don (1832: 17) .

LECTOTYPE (designated by Green (1958: 511)):—[ JAPAN.] Living plants sent by P. F. B. von Siebold from Japan to Java and cultivated in Hortus Bogoriensis, herbarium specimen prepared by C. L. Blume ( L).

The full list of synonyms is given by Lu (1992), Yamazaki (1993), Chang et al. (1996) and Xiang & Ji (2004). Green (1958) provided an extensive discussion on some of the synonyms.

Description:—Shrubs or small trees 1–8(15) m high, bark smooth, pale, branches puberulous when young. Leaves opposite; petiole puberulous at least when young, 4–14 mm long; blade thick coriaceous, glabrous with midrib puberulous adaxially especially at base, generally punctate, ovate to elliptic or rarely obovate, 3–7 cm long, 1–3 cm wide, margin thickened, entire or with up to 3(5) large strong spiny teeth per side, teeth 3–11 mm long, apex acute and usually aristate, base cuneate or broadly cuneate and slightly decurrent into petiole; secondary veins 4–7 per side, reticulate venation more or less visible above and below. Inflorescence axillary, fasciculate, of 1–2 cymes with 5–8 flowers per cyme. Bracts 2–3 mm long, slightly puberulous towards apex or entirely glabrous. Flowers fragrant. Pedicel 3–8 mm long, glabrous or rarely slightly puberulous. Calyx 1.0– 1.5 mm long, with 4 somewhat irregular tooth-like lobes; lobes often slightly erose. Corolla white; tube 1.0–2.0 mm long; lobes 4, 2.5–5.0 mm long. Stamens 2, attached at middle or in lower half of corolla tube; filaments 1.5–3.0 mm long; anthers 1.5–2.5 mm long, about twice as long as broad, with terminal appendage of connective (i.e., supraconnective). Gynoecium 3–4 mm long; ovary superior; style 2 mm long with slightly bilobed capitate stigma. Fruit a drupe, dark purple, ovoid, ca. 15 mm long, ca. 10 mm in diameter; stone slightly obliquely ellipsoid.

Nomenclatural notes: — Don (1832) published the species name Ilex heterophylla based on the description and material of " Ilex aquifolium var. heterophylla Ait. ?" in Blume (1826). Green (1958) indicated that the holotype of Ilex heterophylla is a specimen at L collected from a plant cultivated by Blume in the Bogor Botanical Gardens. However, the original material of this species name also includes herbarium specimens sent from Japan to Java (along with the living material) by P.F.B. von Siebold (e.g. L: L0420196), which were identified by Siebold as " Ilex aquifolium var. heterophylla Pers. " in agreement with Blume (1826). This means that the indication of the " holotype " by Green (1958) is inadvertent lectotypification.

Taxonomic notes:— The collection studied here demonstrates intermediate morphology between O. heterophyllus and O. fragrans . Its inflorescence bracts are slightly shortly hairy outside and sparsely hairy inside, which conforms O. heterophyllus , whereas O. fragrans is characterized by glabrous bracts. The leaf blades are up to 4.8 cm long and up to 1.8 cm wide, which fits O. heterophyllus well, although such small blades were also rarely recorded in O. fragrans . However, the leaves (including petioles and blades) are glabrous, pointing to O. fragrans , whereas O. heterophyllus is known to have puberulous petioles (but sometimes glabrescent with age) and adaxially puberulous midrib. Finally, the studied collection shows the style about 1 mm long, which is deeply divided into 2 subulate stigma lobes, in contrast to the style of O. heterophyllus described as being 2 mm long and bearing a capitate stigma; on the other hand, the gynoecium morphology is insufficiently documented in some species of Osmanthus , and it is not described for O. heterophyllus by e.g. Chang et al. (1996). In particular, there is a possibility that the studied flowers lack a capitate stigma because they are male, i.e. their gynoecia are pistillodes (cf. Chang et al. 1996: Fig. 245-2); the pistillodes apparently bear no significance for the species discrimination in Osmanthus . Taking these considerations into account (and especially the size of leaf blades), we believe that O. heterophyllus is the most plausible identification for the collection in question.

In addition, Xu et al. (2007) pointed out that among the 19 species of Osmanthus studied by them only O. heterophyllus is characterized by leaves with a marginal vein. The Vietnamese collection indeed shows a presence of a marginal vein at least in some cases.

The Vietnamese population belongs to the type variety of O. heterophyllus , which is known to have the same distribution area as the entire genus. The second accepted variety, O. heterophyllus var. bibracteatus ( Hayata 1920: 71) Green (1958: 516) , is endemic to Taiwan ( Green 1958, Chang et al. 1996).

Specimens examined:— VIETNAM. Thanh Hoa Province: Ba Thuoc District, Co Lung Municilality, Eo Dieu village , primary evergreen seasonal broad-leaved closed submontane forest on top of rocky ridge composed with crystalline marble-like highly eroded limestone, around point 20°26'06''N, 105°13'51''E, 900–1000 m, 25 September 2003, L. Averyanov, D. T. Doan, J. Regalado, N. T. Vinh HAL 3478 ( HN: HN000070397 ; MW: MW1046193 ) .

Distribution:— Japan, Taiwan, Vietnam (Thanh Hoa) ( Fig. 6 ).

Ecology and habitat:— In Vietnam, O. heterophyllus grows in forests at elevations of 900–1000 m a.s.l. Flowering in September.

Figures

FIGURE 1. Phylogenetic tree obtained from the Bayesian analysis of the nrITS dataset. Numbers near branches indicate posterior probabilities (PP) / bootstrap percentages in the maximum parsimony analysis (BS); “-” indicates absence of the branch in the maximum parsimony analysis. Scale bar shows number of substitutions per site. The specimens studied in the present paper are shown in boldface; accessions with doubtful identification are shown in gray.

FIGURE 4. Osmanthus heterophyllus (apparently a male individual). A. Flowering branches. B. Inflorescences. C, D. Leaves, adaxial and abaxial side. E. Inflorescence bract. F. Longitudinally opened flower. G. Calyx and gynoecium (side view). Averyanov et al. HAL 3478. Photos by L.V. Averyanov (A, B) and Bui Hong Quang (C–G, from dried specimen).

FIGURE 5. Osmanthus heterophyllus (apparently a male individual). A. Flowering branch. B. Inflorescence in leaf axil. C. Flower (side view). D, E. Flowers (top view). F. Corolla lobe. G. stamens. Drawn from Averyanov et al. HAL 3478 (HN) by Le Kim Chi.

FIGURE 6. Distribution of Osmanthus heterophyllus and O. yunnanensis in Vietnam.