Pelargonium tortandrum E.M.Marais, 2024

Marais, Elizabeth M., 2024, Three new species of Pelargonium, section Hoarea (Geraniaceae) from the Western Cape Province, South Africa, Phytotaxa 675 (1), pp. 69-78 : 75-77

Pelargonium tortandrum E.M.Marais , sp. nov. ( Fig. 5 ).

Diagnosis:— Similar to P. luteum and P. fumariifolium because all three species have linear to narrowly spathulate petals with pale pink Vshaped markings on the posterior two and the filaments of the lateral stamens are twisted so that the pollen surfaces are facing to the front. They differ in that P. tortandrum has three or four, seldom five fertile stamens and simple, seldom trifoliolate, ovate, prostrate leaves, P. luteum has always five fertile stamens and erecto-patent, pinnately compound leaves with the lamina elliptical in outline, and P. fumariifolium has only two fertile stamens, which are in the lateral position, and five very long staminodes in the anterior position, both these characteristics are unique within Pelargonium ( Marais 1981, 1994). The latter has also erecto-patent, pinnately compound leaves, but the lamina is trullate in outline.

Type:— SOUTH AFRICA. Western Cape: Farm Gannabosvlakte near Langvlei siding, between Worcester and Robertson, (3319 DC), 25 August 2006, E. M. Marais 454 (holotype NBG!; isotypes K!, MO!, PRE!) .

A deciduous geophyte 90–210 mm tall when in flower. Tuber : turnip-shaped or elongated, usually moniliform root, covered with flaking dark brown periderms, 10–40 mm long and 8–15 mm diam. Leaves: radical, rosulate, simple, seldom trifoliolate, petiolate; lamina or main pinna elliptic or ovate, 19–30 × 12–19 mm, bases cuneate, apices obtuse, margin entire, adaxially and abaxially glabrous, with appressed curly hairs abaxially along the veins, margins ciliate; petiole prostrate, 10–20 mm long and 1.0– 1.5 mm diam., hirsute with distally appressed hairs; stipules subulate, 7 × 1 mm, ciliate, adnate to petioles, apices free. Inflorescence: scape 20–130 mm long, green, densely covered with glandular hairs interspersed with appressed curly hairs and long appressed non-curly hairs, branched, bearing 4–6 pseudo-umbellets with (6–)7–9(–11) flowers each; peduncles 50–90 mm long, 1–2 mm diam., covered with glandular hairs of different length, sparsely interspersed with distally appressed curly hairs; bracts lanceolate, 3–4 × 1–2 mm, adaxially and abaxially hirsute, flower buds, flowers and fruits erect. Pedicel ± 0.5 mm long. Hypanthium 18–22 mm long, 3.0–3.6 times the length of the sepals, pale reddish brown, densely covered with distally appressed curly hairs interspersed with glandular hairs. Sepals 5, posterior one erect, others reflexed, lanceolate, apices acute, 5–6 × 1.0– 1.5 mm, reddish brown to green, abaxially densely covered with distally appressed curly hairs interspersed with glandular hairs. Petals 5, pale yellow, patent during anthesis; posterior two with pale pink V-shaped markings, linear or narrowly spathulate, 14–15 × 2.0– 2.5 mm, length/width ratio 6–7, bases narrowly cuneate, apices rounded, reflexed at 90°; anterior three linear or narrowly spathulate, 11–12 × 1.5–2.0 mm, bases narrowly cuneate, apices rounded. Stamens 10, basally connate, staminal column ± 1.5 mm long, smooth, white; fertile stamens 3–4 (seldom 5), posterior filament 2.5 mm long, lateral two filaments 6.5 mm long, anterior two filaments 6.5 mm long, white, free filaments of lateral stamens twisted so that pollen surfaces of the anthers are turned to the front, lateral and anterior stamens more or less the same length as the sepals, protruding from the flower; staminodes ± 2 mm long; anthers red, 1 mm long, pollen orange. Gynoecium: ovary 2–4 mm long; style 1–4 mm long, dark pink; stigma branches 1–2 mm long, dark pink. Fruit: bases of mericarps 4 mm long, with prominent glandular hairs, tails 19–22 mm long. Chromosome number: unknown.

Flowering period:— From October to November.

Habitat:— It grows on clay soil in karroid vegetation on foothills or in open areas on dry flats in mainly a winter rainfall area with an annual precipitation of 200–500 mm.

Distribution:— So far only known from a small area in the Robertson Karoo ( Fig. 6 ).

Diagnostic characters:— Pelargonium tortandrum is a small geophyte with pale yellow flowers and simple, seldom trifoliolate prostrate leaves. The flowers have linear to narrowly spathulate petals with pale pink V-shaped markings on the posterior two, and three or four, seldom five fertile stamens with the filaments of the lateral two stamens twisted so that the pollen surfaces are facing to the front ( Fig. 5a ).

Conservation status:— Pelargonium tortandrum occurs in a small area next to the Afrimat, Cape Lime, industrial development at Langvlei and can be under threat if this development should expand in future. Given the low values of Area of occupancy (AOO) and Extent of occurrence (EOO), together with the detected possible threat, this species will probably fall in an IUCN (2024) category with high risk of extinction. Nevertheless, further exploration is necessary to determine population size and dynamics. Therefore, the species is here provisionally indicated as Data Deficient (DD), even if in similar cases rare and threatened species are often assessed as Critically Endangered (CR) ( Perrino et al. 2023; Yan & Hao 2024).

Etymology:— The specific epithet refers to the twisted filaments of the lateral stamens (Latin torti -, twisted; Greek -andrus, male).

Notes:— The distribution of P. tortandrum is very small if compared to the wide distribution of the related P. fumariifolium . The latter occurs from Kaus Mountains in Namaqualand in the north to Ceres-Karoo in the south and Whitehill in the east. This overlaps with the distribution of the second related species, P. luteum around Nieuwoudtville and Calvinia and boardering that of P. tortandrum in the Robertson Karoo ( Fig. 6 ). All three species occur in the winter rainfall area with a similar annual precipitation of 200–500 mm and all three species flower from October to November.

Additional specimens examined:— SOUTH AFRICA, Western Cape: Farm Gannabosvlakte near Langvlei siding, between Worcester and Robertson (3319 DC), 24 October 2006, E. M. Marais 457a ( STEU) ; 1.5 km E of Langvlei siding (– DD), August 2005, C. Craib s.n. ( STEU) .

Figures

FIGURE 5. Pelargonium tortandrum: (A) flowers; (B) plants with leaves in habitat. Photographs by Matije Strilc.

FIGURE 6. Geographical distribution of Pelargonium tortandrum, z; P. fumariifolium, *; and P. luteum,Ɨ.