Pelargonium hammansbergense E.M.Marais & A.le Roux, 2021

Marais, Elizabeth M. & Roux, Anso Le, 2021, Two new species of Pelargonium (Geraniaceae) from the Western and Northern Cape Provinces (South Africa) and their position within P. section Hoarea, Phytotaxa 516 (1), pp. 92-100 : 94-96

Pelargonium hammansbergense E.M.Marais & A.le Roux , sp. nov. ( Fig. 2 ).

Diagnosis: ─The yellow flowers with prominent dark red blotches on the posterior petals are similar to those of P. moniliforme Harvey (1860: 264) and P. vinaceum E.M. Marais (2000: 190) , but P. hammansbergense differs in that the erect to patent leaves are simple to pinnately divided, the scape branched, and the anterior stamens more or less the same length as the sepals. Both P. moniliforme and P. vinaceum have simple to ternate, prostrate leaves, unbranched scapes and the anterior stamens always longer than the sepals.

Type: ─ SOUTH AFRICA. Western Cape: Hammansberg, on farm Lemoenpoort, south of Worcester (3319 CD), 14 October 2014, Le Roux & De Wet 1305 (holotype NBG!; isotypes K!, PRE!) .

A deciduous geophyte 90–110 mm tall when in flower. Tuber: turnip-shaped, moniliform root covered with flaking dark brown periderms, 12–15 mm long and 10–15 mm diam. Leaves: radical, prostrate to erecto-patent, vary from simple to trifoliolate to finely pinnately divided, petiolate; lamina or main pinna of simple or trifoliolate leaves elliptic to ovate, 25–30 x 16–18 mm, bases cuneate, apices obtuse, margins entire to irregularly crenate, minor pinnae ovate, 15–16 x 8–9 mm, bases cuneate, apices obtuse, segments of finely divided laminae 2 mm wide, adaxially covered with short erect stiff hairs, abaxially glabrous, margins sparsely ciliate with soft hairs; petiole patent-erect, pale green, 20–90 mm long, covered with appressed curly hairs and short glandular hairs, sparsely interspersed with appressed stiff hairs; stipules subulate, ciliate, 7–10 mm long, adnate to petiole, apices free. Inflorescence: scape 15–30 mm long, covered with distally appressed curly hairs interspersed with long glandular hairs; branched, bearing 2–3 pseudo-umbellets with 5–10 flowers each; peduncles 25–60 mm long, 1–2 mm diam., pale green, covered with distally appressed curly hairs interspersed with long glandular hairs; bracts lanceolate, 2–3 mm long, abaxially densely hirsute with appressed stiff hairs interspersed with glandular hairs; flower buds, flowers and fruits erect. Pedicel ± 0.5 mm long. Hypanthium 20–29 mm long, 3.0–4.8 times the length of the sepals, pale reddish green, densely covered with appressed curly hairs, interspersed with long glandular hairs. Sepals 5, posterior one erect, others reflexed, 6.0–7.5 x 1.5–3.0 mm, lanceolate, reddish green with membranous margins, abaxially covered with glandular hairs, sparsely interspersed with appressed curly hairs. Petals 5, cream-coloured to pale yellow or yellow, spathulate, patent during anthesis; posterior two with prominent wine-red blotches in the centre and claws with or without wine-red feather-like markings, 15.0–17 x 5.0–6.0 mm, length/width ratio 2.8–3.3, apices rounded to shallowly emarginate, bases narrowly cuneate; anterior three 10–13 x 3–5 mm, apices rounded, seldom shallowly emarginated, bases attenuate. Stamens 10, basally connate, staminal column 1.0– 1.5 mm long, smooth, white; perfect stamens 5, posterior filament 3 mm long, lateral two filaments 4.5–5.0 mm long, anterior two filaments 7.0– 7.5 mm long, more or less the same length as the sepals, protrude from the flower, anthers dark red, 1.5–2.0 mm long, pollen orange. Gynoecium: ovary 3.0– 3.5 mm long; style 1.0– 2.5 mm long, pink; stigma with 5 recurved branches, 1.5–1.8 mm long, adaxially dark red. Fruit: a 5-parted schizocarp, bases of mericarps 4 mm long, with glandular hairs, tails 22–24 mm long Chromosome number: unknown.

Flowering period: ─Early spring, during October.

Habitat: ─ It grows on loam slopes in full sun in a Euryops rehmannii Compton (1931: 321) ─ Elytropappus rhinocerotis Lessing (1832: 344) plant community which forms part of the Elytropappus rhinocerotis (Renosterbos) shrubland component of the Winter-rainfall Mountain Mosaic Veld south of Worcester ( Le Roux 2018). The plants occur on the south-eastern slope of Hammansberg (425–430 meters above sea level) where the vegetation is supported by acidic (pH 4.3) rocky loam soil with a considerable percentage of clay ( Le Roux 2018), derived from glacial tillite of the Dwyka Group (Karoo Supergroup) ( Gresse 1997, Gresse & Theron 1992). Annual rainfall (mainly in the winter months) at the site rarely exceeds 220 mm.

Distribution: ─An endemic of the Breede River Valley in the Western Cape, known from Hammansberg on the farm Lemoenpoort and a nearby farm Moddergat south of Worcester ( Fig. 1 ).

Diagnostic characters: ─The spathulate yellow petals and the anterior stamens more or less the same length as the sepals are similar to those of P. aridicola , P. hirtipetalum and P. tripalmatum . Pelargonium hammansbergense is characterized by the prominent dark blotches on the posterior petals and the prostrate to patent-erect simple to pinnately divided leaves. Pelargonium aridicola , P. hirtipetalum and P. tripalmatum have dark red feather-like markings on the posterior petals. Pelargonium hirtipetalum is known for the soft hairs covering the petals, P. aridicola for the fine pinnately divided leaves and P. tripalmatum for its tripalmate compound leaves.

Conservation status: ─Although P. hammansbergense occurs in a small area south of Worcester, it grows in mountainous areas currently not applied for agricultural activities.

Etymology:− The specific epithet refers to the locality of the type specimen.

Notes: ─Although the yellow flowers with the prominent dark red blotches on the posterior petals and the protruding stamens of P. hammansbergense resemble those of P. moniliforme and P. vinaceum , the simple to pinnately divided leaves, branched scape and the anterior stamens more or less the same length as the sepals, the first mentioned fit in best with the morphology of the P. aridicola group. Both P. moniliforme and P. vinaceum have unbranched scapes, a characteristic not common in P. section Hoarea and the anterior stamens are always longer than the sepals and protrude from the flower.

Additional specimens examined: ─ SOUTH AFRICA, Western Cape: Hammansberg, on farm Lemoenpoort, south of Worcester (3319 CD), 9 September 2015, E. M . Marais 473 ( STEU!); farm Moddergat (3319 CD), 13 October 1979, G. J . Rossouw 446( A & B) ( NBG!) .

Figures

FIGURE 1.Geographical distributionof Pelargonium tripalmatum Ɨ,P.aridicola, P.hirtipetalum,P.pubipetalum G,P.roseopetalum ‡, P. reflexipetalum  and P. hammansbergense •

FIGURE 2. Pelargonium hammansbergense: (A) flowering plant in habitat; (B) plant with tuber and flowers; (C) plants with leaves in habitat. Photographer:Anso le Roux. (D) mericarp with glandular hairs. Scale bar:1.3 mm.