Oxalis canaliculata Dreyer, Roets & Oberlander, 2017

Dreyer, Léanne L., Roets, Francois & Oberlander, Kenneth C., 2017, Two new Oxalis (Oxalidaceae) species, including 5 varieties, from the Richtersveld of South Africa, Phytotaxa 314 (2), pp. 231-240 : 235-236

Oxalis canaliculata Dreyer, Roets & Oberlander , spec. nov. ( Fig. 3 )

Oxalis canaliculata is characterised by being acaulescent, leaves bearing mostly conduplicate, peltately arranged leaflets, peduncles that bear a single white or yellow flower, and a shallow bulb that is covered in numerous dark brown, shiny, keeled tunics.

Type:— SOUTH AFRICA. Northern Cape Province, Richtersveld, top Helskloof, 2816 BD, M. B. Bayer 1022 (holotype NBG!).

Slender acaulescent geophyte, up to 75 mm tall (much larger in cultivation), sparsely and minutely hairy. Contractile root, if present, not observed. Bulb shallow, ovate to ovoid in longitudinal plane, fusiform, up to 60 × 29 mm, usually much smaller (35 × 28 mm), often slightly asymmetrical in the longitudinal axis, apex and base acute, apex often forming apical beak; tunics sparsely and minutely glandular-hairy, hard, shiny, dark brown, keel-shaped, loosely arranged around bulb, sparsely but distinctly longitudinally veined. Rhizome up to 60 mm long, sparsely and minutely glandular.Above-ground stem absent. Leaves 4–7 per plant, dark green, multifoliolate, sparsely and minutely glandular-hairy to glabrous, held erect or in varieties prostrate. Petioles filiform to slender, wiry, dark green to brown, sometimes sparsely minutely glandular hairy, up to 60 mm long, 1.2 mm diam. Leaflets 3–15, linear, 9–45 mm long, up to 3 mm wide, epistomatic, more or less conduplicate, often falcate, emarginate, sometimes with two orange apical calli, peltately arranged around apex of petiole; petiolules absent or very short. Peduncles 1-flowered, up to 120 mm long, dark green, sometimes minutely glandular hairy. Bracts 2, below, at or above middle of peduncle, but never close to calyx or base of peduncle, 3.5 × 0.5 mm, alternate, linear to filiform, acute, purple-streaked, margins often sparsely glandular hairy. Flowers white or yellow. Sepals 5, lanceolate, acuminate, up to 9.5 × 2.0 mm, often sparsely glandular hairy, purple-streaked, ecallose. Corolla up to 25 mm long, with short funnel-shaped yellow tube; petals 5, 23 x 12 mm, claw cuneate, lamina obovate, apices rounded to truncate, glabrous, ecallose. Stamens 10, in 3 series, 2 series per plant, the shortest level 2.5 mm long, the middle level 4 mm long and the longest level 6.5–7.0 mm long, filaments basally connate, glandular, longest filaments with short, blunt teeth, up to 0.5 mm long. Ovary 5-locular with 3–5 ovules per locule, 2.5 mm long, narrowly ovoid, ecallose, glandular-hairy; styles 5, separate, in three series with one series per plant, shortest level 2.5 mm long, middle level 4–5 mm long, longest level 6.5 mm long, erect, glandular-hairy; stigma greenish yellow, fimbriate. Fruit a capsule, longer than sepals, up to 11 × 3.5 mm. Seeds without endosperm. Pollen tricolpate, tectum reticulate with scattered intra-luminary bacules. Known flowering time June to September.

Etymology:— The name refers to the narrow, channelled, conduplicate leaflets.

Habitat:— Although widespread throughout the Richtersveld it always grows in full sun in very dry desert or semi-desert conditions with an average annual rainfall of about 150 mm ( Fleminger 2008). It prefers rocky clay soils, but has also been observed on less rocky flats and quartz patches.

Additional material studied (paratypes):— SOUTH AFRICA. Northern Cape Province, Richtersveld Conservancy, Eksteenfontein , 510 m, 16 June 2012, Oberlander, Roets & Dreyer 2012/06-34 ( STEU!) ; 3 km east of Eksteenfontein , 570 m, 16 June 2012, Oberlander, Roets & Dreyer 2012/06-33 ( NBG!) ; Richtersveld National Park, 1 km from R14 turn-off to Kokerboom Campsite , 420 m, 5 July 2011, Oberlander, Roets & Dreyer 2011/07-14 ( BOL!) ; Richtersveld Conservancy, Valley between Cornelsberg and Richtersberg, 560 m, 17 June 2012, Oberlander, Roets & Dreyer 2012/06-45 .

Remarks:— Oxalis canaliculata is diagnosed by being acaulescent, with a shallow fusiform bulb and a peltate, multifoliolate leaflet arrangement. This species is widespread and locally abundant across much of the Richtersveld National Park and Conservancy. Two varieties, clearly related, but morphologically distinct, are described below.

Figures

FIGURE 3. Oxalis canaliculata. A. Typical habitat in the Richtersveld National Park and Conservancy. B. Yellow-flowered form of O. canaliculata var. canaliculata in cultivation.C.White-flowered form of O. canaliculata var. canaliculata in cultivation.D. O. canaliculata var. graniticola growing in cracks in granite boulder. E. O. canaliculata var. graniticola in cultivation. F. Close-up of flower of O. canaliculata var. trifoliolata in the field. G. Bulb of O. canaliculata var. canaliculata. Scale bars = 20 mm. Photographs by F. Roets.