Oxalis rosettifolia Dreyer, Roets & Oberl., 2013

Dreyer, Léanne L., Roets, Francois & Oberlander, Kenneth C., 2013, Two new Oxalis (Oxalidaceae) species from the Richtersveld National Park, South Africa, Phytotaxa 89 (2), pp. 53-63 : 58-60

Oxalis rosettifolia Dreyer, Roets & Oberl. , spec. nov. ( Figure 2 )

Oxalis rosettifolia is distinguished by its very flat basal rosette of leaves. The yellow or cream flowers are carried on very long peduncles that spread outward from the center of the rosette. The bracts on the peduncle are variable in size, with some bracts much enlarged, conspicuous and distinctly spathulate. This species has long, narrow floral tubes that are distinctly flask-shaped.

Type:— SOUTH AFRICA. Northern Cape Province: Richtersveld National Park, Kokerboomkloof , 500 m from campsite, 28°17.881S, 17°17.457E, 560 m, 17 July 2011, Roets, Dreyer & Oberlander 2011 /07-17 (holotype STEU!, isotypes NBG!, BOL!)

Geophyte, up to 300 mm tall, aggregated into clumps. Bulb irregularly ovoid, with contractile root, 30–50 ×10– 6 mm, apical beak a third to half of total bulb length, with prominent ridges that are crenate in cross section, young bulbs triangular in cross-section, with three prominent ridges, tunics pale- to blackish-brown, glabrous, surface pattern finely reticulate. Rhizome vertical, thin, white, 30–40 mm long, adventitious roots along entire length, glandular-hairy, upper rhizome nodes with pale, glabrous, semi-amplexicaul scales; sheath absent. Above-ground stem absent. Leaves many per plant, arranged in a flat, prostrate basal rosette, trifoliolate; petioles variable in length, up to 100 mm long, finely to sparsely hairy over entire length; leaflets distinctly petiolulate, obcordate, 6–10 × 6–14 mm, both surfaces glabrous to sparsely hairy along main veins, margin hairy. Peduncles 1–5 per plant, each with 2–4 terminal flowers, more than twice as long as petioles, up to 250 mm long, at least twice as thick as petioles, sparsely hairy; bracts very variable on the same peduncle, shortest l– 4 mm long, longest up to 13 mm long, smaller bracts linear-lanceolate, hairy, bicallose, with acute to rounded apices, larger bracts distinctly spathulate, hairy, with calli scattered across both surfaces, becoming more densely callose towards margins, with acute to rounded apices. Pedicels slender, about as thick as petioles, sparsely hairy, 20–45 mm long when mature. Sepals 6.0 ×1.0 mm, lanceolate, apex acute, with two small, orange calli, sparsely hairy. Corolla 18–22 mm long, yellow or cream with long, narrow, flask-shaped, light yellow tube, tube usually more than half the length of corolla, petals oblanceolate, apex truncate, glabrous, ecallose. Stamens in 3 series, 2 series per plant, the shortest level 3.5–4 mm, the middle level 4.5–5 mm and the longest level 6.5–7 mm long, basally connate; anthers oblong, yellow; filaments pale, glabrous; filament teeth 2.2 mm long from base, apically acute. Ovary 3.0 mm long, narrowly ovoid, densely hairy on upper half, with few scattered hairs on lower half, 5-locular with many ovules per locule; styles 5, separate, in three series with one series per plant, shortest level 3.5 mm long, middle level 5 mm long, longest level 7.5 mm long, erect, densely hairy; stigmas green, fimbriate. Fruit not seen. Seeds not seen.

Distribution:— Oxalis rosettifolia is known from the type locality only. The two populations of this species were found growing in shallow granite soils near Kokerboomkloof Campsite in the Richtersveld National Park. Both populations included yellow- and cream-flowered plants that were in full flower in mid- July. All three stylar morphs were observed in these populations.

Notes:— The specific epithet of O. rosettifolia refers to the flat basal rosette formed by the leaves of this species.

Figures

FIGURE 2. a. Desert vegetation at Kokerboomkloof Campsite in the Richtersveld National Park; b–d. Oxalis nivea; b. Habitus; c. Flowers; d. Bulb; e–h. O. rosettifolia; e. Habitus; f. Flowers (cream-coloured form); g. Flowers (side view of yellow-coloured form); h. Bulb. Scale bars = 50 mm