Leptonychia usambarensis K.Schum. [family STERCULIACEAE]

Herbarium
Royal Botanic Gardens, Kew (K)
Collection
Flora of Tropical East Africa
Resource Type
Reference Sources
Entry From
Flora of Tropical East Africa, page 1, Author: MARTIN CHEEK AND LAURENCE DORR
Names
Leptonychia usambarensis K.Schum. [family STERCULIACEAE], in E.J. 33: 313 (1904); T.T.C.L.: 600 (1949); K.T.S.: 549 (1961); Dows.-Lem. & F. White in B.J.B.B. 60: 84 (1990); K.T.S.L.: 166, fig. (1994); Schulman et al., Trees Amani Nat. Res.: 150–151 (1998); F. White et al., Evergreen For. Fl. Malawi: 562, fig. 197, D, E (2001). Types: Tanzania, Lushoto District: Usambara, Derema, Scheffler 155 (B†, syn.) & Kwai, Albers 301 (B†, syn.)
Leptonychia usambarica Engl. [family STERCULIACEAE], [in N.B.G.B. 3: 84 (1900), sphalm. pro “ usambarensis ”]
Leptonychia schliebenii Mildbr. [family STERCULIACEAE], [, nom. nud., in sched., based on Schlieben 2860]
Information
Shrub or trees, 3–20 m tall, 30–40 cm DBH; bark grey to brown, smooth or rough with numerous lenticels, slash light yellowish-brown, rapidly turning dark rusty brown; young branchlets minutely stellate-puberulous. Leaves oblong to elliptic or obovate-oblong, 4–22 cm long, 1.5–9 cm wide, apex acute to acuminate, margin entire to repand, base rounded or widely cuneate, glabrous above, ± glabrous below except for scattered appressed stellate hairs on the blade and scattered appressed multi-rayed hairs on midvein and major veins below, shiny dark green and nitid above, somewhat paler and glaucous (especially on nerves) below; palmately 3–5-nerved from the base with 4–6 pairs of ascending 2° nerves; domatia in vein axils composed of broadly ovate to orbicular pits ringed by simple hairs; petiole 5–15 mm long, ± pulvinate apically, puberulous to glabrescent; stipules acicular, to 4 mm long, puberulous, caducous. Cymes few-flowered; peduncle 6–8 mm long (to 15 mm in fruit); pedicels 6–15 mm long, stellate-pubescent, articulate; bracts to 2 mm long. Flowers white fading to yellow, whitish-green or yellow-green. Sepals greenish-white, subulate, sometimes unequal in length, 7–13 mm long, 2–3 mm wide, scattered stellate hairs externally, puberulous internally. Petals obcordate to rotund, 1.2–1.5≈1.2–1.8 mm, apex ± truncate, ciliolate, a few stellate hairs externally, ± glabrous internally. Staminal tube 0.7–1.3 mm long with 5 phalanges of 2 stamens each (10 total) and 3–4 filament-like long staminodes (15–20 total) exceeding the fertile stamens in length, long staminodes crispate (curled), to 6.8 mm long; phalanges alternating with 5 gland-like short staminodes, ± 0.5 mm long; fertile stamens with filaments to 4–5.3 mm long, filaments erect; anthers ± 0.7 mm long; occasionally deviating specimens with 20 stamens total and no filament-like staminodia. Ovary 1.8≈1.2 mm, hirsute, 3(–4)-locular, (3–)4–5 ovules per locule; styles ± 5 mm long, pubescent to the apex; stigmas barely lobed. Capsules yellowish-green at maturity, globose, asymmetrical, 10–17 mm long, 8–15 mm in diameter, shortly apiculate, papillate or muricate, densely stellate-pubescent, becoming glabrescent in age, loculicidal; seeds black, 1 per locule, 9–13 mm long, 7–8 mm in diameter, smooth, lustrous. Fig. 18, p. 103.
Range
DISTR. K 4, 7; T 3, 6, 7
Altitude range
200–350(–1900) m
Distribution
KENYA Teita District Chawia forest, fr. May 1985, Beentje et al. 868! & Ngangao Forest, 9 May 1985, Faden et al. 236!KENYA Kwale District Shimba Hills, Lango ya Mwagandi [Langomagandi], fl, fr 17 Mar. 1991, Luke & Robertson 2721!TANZANIA Pare District Chome Forest Reserve, fr. 27 Feb. 2001, Mlangwa et al. 1410!TANZANIA Tanga District Kwamgumi Forest Reserve, fr 13 June 2000, Mwangoka 1372!TANZANIA Iringa District Mwanihana Forest Reserve, fl. 8 Sep. 1984, D.W. Thomas 3657!
Distribution (external)
?Mozambique (Luke et al. 9915, n.v.)
Malawi (Misuku Hills)
Notes
LOCAL USES. The bark of L. usambarensis is used for tying (Semsei 806).  This species is relatively common (20 or more specimen-sites) and fairly widespread. However it is likely that it will rate as threatened under criterion A when quantitative data are available for its recent loss of habitat, so here it is asssessed as near threatened. Cordeiro and Howe (Proc. Natl. Acad. U.S.A. 100: 14052–14056 (2003)) documented the negative impact of forest fragmentation on L. usambarensis, which is dependent upon birds for seed dispersal. Forest fragmentation in the mountains of East Africa is likely to contribute to local extinction of this (and other) tree species.  Vegetatively, L. usambarensis and L. mildbraedii are very difficult to separate since they share the same vestiture, hair types, and domatia. The leaves of the former tend to be larger and less frequently acuminate than those of the latter, but there is overlap in these characters. Also, the pit domatia of L. usambarensis tend to be ringed by simple hairs and while those of L. mildbraedii for the most part are not, occasionally they are. In flower, most specimens of L. usambarensis and L. mildbraedii appear to be readily distinguishable by androecial characters (see key), but the fact that the Asian L. caudata (G.Don) Burret exhibits both of the staminodial types seen in these East African species, as well as intermediate types (see Veldkamp and Flipphi, 1987, fig. 3), tempers somewhat my enthusiasm for these key characters. In addition, a number of specimens of L. usambarensis have deviating androecial types. Notably Mwangoka 1771 and Schlieben 2860 lack filament-like staminodia and appear to have as many as 20 anthers, the anther sacs on those of the former are without pollen but those of the latter have pollen. Other specimens have anomalous flower buds: Beentje et al. 868 has mature fruit but also flower buds with short, fleshy sepals, reduced petals, 10 sessile anthers, and no visible ovary, ovules or style. Specimens with similarly shaped flower buds (e.g., Mwangoka 1112) show evidence of being parasitized by insects. All of this forces me to conclude that L. usambarensis and L. mildbraedii are closely-related vicariant species. Found in similar, higher elevation habitats, populations of these two species are now geographically isolated and presumably will continue to diverge.
Leptonychia usambarensis K.Schum. [family STERCULIACEAE]
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