Heliophila clarkii Al-Shehbaz, 2020

Al-Shehbaz, Ihsan A., 2020, Ten new species in the southern African genus Heliophila (Brassicaceae; Cruciferae), Phytotaxa 434 (1), pp. 65-88 : 70-72

Heliophila clarkii Al-Shehbaz , sp. nov.

Diagnosis:— Heliophila clarkii differs from the other annual congeners (with undivided linear to filiform leaves and slightly moniliform fruit and without the paired glands at the bases of leaves and pedicels) by having puberulent stems below the cotyledonary scars, papillate lateral stamens bases and adjacent petal margins, and usually geniculately reflexed fruiting pedicels.

Type:— SOUTH AFRICA. [Northern Cape, Namakwa, Karoo Hoogland], Sutherland District, Summit of the Swaarweerberg, Roggeveld, Farm Geelhoek 103, 32º25ʹ39ʺS, 20º34ʹ53ʺE, 1828 m, 12 Sep. 2008, V. R. Clark & R. O’Connor 75 (holotype, MO-6334883, isotype, GRA). Figure 3 .

Description: —Plants annual, not glaucous. Trichomes straight, 0.05–0.1 mm long. Stems herbaceous, 6–15 cm tall, smooth, terete, erect, simple or branched at or above middle, puberulent primarily below the cotyledon scars. Basal leaves soon withered; cauline leaves not fleshy; petiole absent; blade simple, linear to filiform, 0.5–3.5 cm × 0.5–1 mm, entire, without a pair of stipule-like glands at node, glabrous, base not auriculate, not decurrent or articulate. Racemes terminal, corymbose, 6–18-flowered, elongated in fruit, not secund; rachis straight, glabrous; fruiting pedicels without a pair of basal bract-like glands, not articulate at base, glabrous, slender, usually geniculate-reflexed at base, curved, persistent, lowermost 6–12 mm long; buds oblong. Sepals ascending, oblong, 3–3.5 mm long, glabrous, persistent, lateral pair not cucullate at apex, saccate at base, median slightly cucullate, not saccate. Petals white, broadly obovate, 6–7 × 3.5–4 mm, ascending, rounded at apex, with papillate lower margin facing lateral stamens; claw obsolete or to 1 mm long. Stamens slightly tetradynamous; filaments 1.5–2 mm long, lateral pair papillate proximally, median pairs unappendaged; anthers ovate, ca. 1 mm long, not apiculate at apex. Nectar glands lateral, median glands absent. Ovary glabrous; ovules 5 or 6 per ovary. Fruit (immature) silique, capsular, linear, 1.2–1.5 cm × 1–1.5 mm, latiseptate, glabrous, submoniliform, slightly constricted along replum, smooth, strongly reflexed; valves papery midvein distinct, lateral veins obscure; gynophore obsolete; style in fruit 1.5–3 mm long, cylindrical, slender, glabrous; stigma entire. Seeds (immature) uniseriate.

Phenology: —Flowering September through October.

Distribution: — Heliophila clarkii is known only from the type and paratype collections from the Karoo Hoogland municipality of the Northern Cape Province.

Etymology: —The species is named in honor of the South African botanist Vincent Ralph Clark who collected many species of Heliophila for my study.

Additional specimens examined (Paratypes): — SOUTH AFRICA. SOUTH AFRICA. Northern Cap e, [Karoo Hoogland]: Sutherland District , Roggeveld, Farm Elandsfontein 47, 32º12ʹ5ʺS, 20º34ʹ53ʺE, 1566 m, 8 Oct. 2008, V. R. Clark & G. Coombs 761 ( GRA, MO) ; Klipfontein , SW of Sutherland, M. F. Thompson 1791 ( PRE). Hantam (as Calvinia): Hantam Mt top, R. Marloth 12799 ( PRE) .

Habitat: —Sandy-clay soil in Karoo shrubland.

Discussion: — Heliophila clarkii is most closely related to the new species H. roggeveldensis (see below) which it resembles in the annual habit and in having puberulent stems below the cotyledons scars, linear to filiform leaves without the paired nodal glands, often geniculate-reflexed mature fruiting pedicels lacking the paired basal glands, and somewhat submoniliform fruit. It differs from H. roggeveldensis in having slender (vs. rather stout) lowermost fruiting pedicels 6–10 (vs. 3–4) mm long, proximally papillate (vs. glabrous) lateral filaments and adjacent petals margins, and distinctly larger flowers with saccate (vs. not saccate) lateral sepals 3–3.5 (vs. 1.2–1.5) mm long, and broadly obovate (vs. oblanceolate) petals 6–7 × 3.5–4 mm (vs. 1.5–2 × 0.5–0.7 mm).

Both novelties grow in the Karoo Hoogland of the Northern Cape and are remotely related to the exclusively Western Cape-endemic H. pusilla s.l., a species divided by Marais (1970) to include four varieties. These varieties differ drastically from both H. clarkii and H. roggeveldensis in having completely glabrous (vs. always puberulent lowermost stems below the cotyledonary scars) and divaricate to ascending or very rarely horizontal-descending (vs. usually geniculate-reflexed) fruiting pedicels, and strongly (vs. slightly) moniliform fruit. In all of the 928 plants of H. pusilla that I critically examined, none has puberulent lower stems, and none of those with mature or developing fruits has geniculate-reflexed fruiting pedicels.

Heliophila clarkii resembles some of the rare forms of H. acuminata (Ecklon & Zeyher 1835-1835: 57) Steudl (1840: 742) with exclusively undivided leaves. It differs from the latter, which is restricted to the Western Cape, by having completely glabrous (vs. almost always basally puberulent) fruiting pedicels, submoniliform (usually strongly moniliform) and non-secund (vs. most frequently secund) fruit, white (vs. purple, mauve, or sometimes white) flowers, valve apex not extending (vs. extending 0.5–2 mm) over styles 1.5–3 (vs. 3–5(–7) mm long, ovaries with 5 or 6 (vs. 8–20) ovules, and papillate (vs. appendaged) lateral filaments and adjacent petal margins.

Figures

FIGURE 3. Heliophila clarkii.A. Plant. B. Portion of stem below cotyledon scars. C. Lateral sepal. D. Petal. E. Lateral stamen. F. Fruiting pedicel and immature fruit. Drawn by Al-Shehbaz from holotype (MO-6334883).