Trachyandra bulbosa Boatwr. & J.C.Manning, 2013

Boatwright, James Stephen & Manning, John Charles, 2013, Two new species of Trachyandra sect. Liriothamnus (Xanthorrhoeaceae, Asphodeloideae) from the Western and Eastern Cape Provinces of South Africa, Phytotaxa 155 (1), pp. 59-65 : 62

Trachyandra bulbosa Boatwr. & J.C.Manning , sp. nov. ( Fig 2 A–E )

Resembling T. gracilenta in its habit, narrow leaves, simple inflorescences, and scabridulous capsules, but differing in the bulbous rhizome, fibrous leaf bases, microscopically puberulous leaves, and maculate tepals.

Type: — SOUTH AFRICA. Western Cape (2917): summit of Bulletrap Pass in boulder field, (– BC), 8 August 2013, J. S . Boatwright & J. C . Manning 704 (holotype NBG!, isotype K!) .

Deciduous geophyte, 100–200 mm high. Rhizome short, compact and swollen, hard and woody in texture, forming an irregular, bulbous structure with one or multiple shoots, roots cylindrical, felted. Cataphylls surrounding shoots, membranous and colourless, acute and prominently veined. Leaves 4–7, subterete, 100– 150 × 1.0– 1.5 mm, leathery, somewhat flexuous, minutely puberulous, dull greyish green, decaying to form a fibrous or ± papery collar 15-20 mm long, sheaths fimbriate at mouth. Inflorescence a simple raceme; peduncle flexed slightly outward and then erect, 1.0– 1.5 mm diam. at base, minutely puberulous; raceme moderately dense, mostly 5–10-flowered, 40–70 mm long; bracts ovate-acuminate, 5–8 mm long, membranous, scabridulous on midrib abaxially at base, margins ciliolate; pedicels suberect, 5–7 mm long, scabridulous. Flowers rotate, white with greenish midribs, tepals transversely maculate, opening in afternoon, sweetly scented; outer tepals elliptical, 8–10 × 2 mm, scabridulous along midrib abaxially, inner obovate, 7–9 × 3 mm. Stamens suberect; filaments filiform, tapering below, white, ± 6 mm long, retrorsely scabrid in distal half, inner filaments minutely puberulous for short distance below scabrae; anthers yellow, outer 1.5 mm long, inner ± 1 mm long. Ovary ovoid, ± 1.5 mm long, green, with ± 7 ovules per locule; style erect, filiform, ± 5 mm long, white. Capsules ellipsoid, 4–5 × 3–4 mm, scabridulous. Seeds not seen. Flowering time: July to early August.

Distribution and ecology: —Known only from the edge of the western escarpment near the summit of Bulletrap Pass north of Springbok in Namaqualand ( Fig. 3 ), Northern Cape, in local populations on southtrending slopes among gneiss scree, with the base of the plants shaded and protected among the stones. The species was collected in Namaqualand Shale Shrubland, a relatively localised vegetation unit restricted to fairly high altitudes in the region and including an unusually high number of endemic taxa ( Mucina et al. 2006). We estimated the total plants seen as under 100 individuals, all threatened by overgrazing by livestock although no actual population loss has yet been documented.

Taxonomic relationships: —An unusual species that accords with sect. Liriothamnus in its horizontal rhizome, cataphylls not completely transformed into collar-like, membranous structures, and in the outer leaves decaying into a fibrous collar at the base but immediately distinguished by the combination of tufted habit and irregular, bulbous rhizome. Branching of the swollen, knobbly, rhizome in T. bulbosa results in small clumps of shoots, each producing one or two unbranched racemes. In sect. Liriothamnus , similar woody and lobed or branched rhizomes are characteristic of Trachyandra adamsonii ( Compton 1931: 10) Obermeyer (1962: 720) , T. aridimontana Manning (1990: 1) and T. involucrata Baker (1876: 311) Obermeyer (1962: 721) . These three species are unique in the genus in their gnarled, shrubby habit and were presumed by Obermeyer (1962) and Manning (1990) to be closely allied but this remains to be established. Other members of the sect. Liriothamnus have compact, unbranched, non-woody rhizomes. Members of sect. Lirothamnus typically have unmarked flowers, and maculate tepals are known only in T. adamsonii (both whorls), T. aridimontana (inner whorl only) and T. bulbosa (both whorls). Trachyandra bulbosa is most likely to be confused with T. gracilenta Obermeyer (1962: 726) , which has similar, narrow leaves with fibrous bases, simple inflorescences, and scabridulous (visible only under 10× magnification) capsules. T. bulbosa is distinguished from it by the bulbous rhizome, microscopically puberulous (vs. villous) leaves and by the maculate (vs. immaculate) tepals. In addition, the leaf bases in T. gracilenta decay into papery strips rather than fibres and the cataphylls are chestnut brown rather than colourless as in T. bulbosa .

Figures

FIGURE 2. Trachyandra bulbosa. A1, Outer tepal; A2, outer stamen; B1, inner tepal; B2, inner stamen. C, Ovary. D, habit and inflorescence. E, leaf shape in cross section. Scale bar represents 2 mm for A1, A2, B1, B2, C; 10 mm for D, E, F.

FIGURE 3. Known geographical distribution of Trachyandra eriocarpa (square) and T. bulbosa (circle).