Pelargonium conradiae J.C. Manning & A.le Roux, 2016

Manning, J. C. & le Roux, A., 2016, Pelargonium conradiae (Geraniaceae), a new species in section Ligularia from Worcester, Western Cape, South Africa *, South African Journal of Botany 105, pp. 313-316 : 314-316

Pelargonium conradiae J.C. Manning & A.le Roux , sp. nov.

Type: South Africa. Western Cape Province, Worcester (3319): Farm Drooge Riviersberg , SE of Brandvlei Cellars (− CB), Sept. 2014, A. le Roux 1150 ( NBG, holo.; K, iso.) .

Deciduous subshrub up to 300 mm high when in flower; stems erect or decumbent, fleshy when young but later woody, initially armed with persistent bases of petioles, later developing flaking bark. Leaves pinnate, green; blade oblong-lanceolate in outline, 10–30 × 8–10 mm, pinnae bipinnatisect, ultimate segments subulate, 2–4 mm long, puberulous and minutely glandular-haired, eglandular vestiture of short, sub-appressed hairs, interspersed with sparse, longer straggling hairs on petiole and rachis; petiole ± as long as lamina, base expanded, becoming cartilaginous and semi-persistent; stipules decurrent on petiole for half to three quarters their length, 4–12 mm long, glabrous with ciliolate margins, becoming cartilaginous and semi-persistent. Infl orescence with one axillary branch, bearing smaller foliar leaves at node; peduncle villous and glandular-haired, eglandular vestiture of moderately dense, short, spreading hairs up to 0.3 mm long mixed with markedly verrucose-based, straggling hairs ± 1–2 mm long; pseudo-umbels 2 or 3-flowered; pedicels ± 1 mm long; hypanthium 10–12 mm long, indumentum similar to peduncle but straggling hairs up to 1 mm long. Sepals oblong, 8–9 × 2–3 mm, green tinged purple, abaxial indumentum as on peduncle. Petals 5, pure white or faintly flushed pink, all unmarked, posterior two erect or reflexed, oblanceolate to obovate, 15–20 × 6–9 mm, obtuse or emarginate, anterior three narrowly oblanceolate, 13–18 × 3–4 mm, obtuse. Fertile stamens 7, filaments white, solitary posterior 11 mm long, two upper laterals 10 mm long, four anterior 12–13 mm long; anthers ± 2 mm long, reddish with yellow pollen. Style wine-coloured (see Figs. 1 and 2 ).

Etymology

The epithet honours Mrs. Hettie Conradie, owner of the farms Drooge Riviersberg and Sandberg on which the new species was collected, in recognition of her avid interest in the flora of the Worcester area, her affection for the veld, and her devotion to conservation farming.

Diagnosis

Pelargonium conradiae is a member of a small group of species allied to P. hirtum and characterised by a subshrubby habit, pinnate leaves with bi- or tripinnatisect pinnae, and white or pink flowers with short hypanthia less than 15 mm long and seven fertile stamens. It is distinguished from other members of the group by the semi-persistent petiole bases with the stipules adnate to the petiole for half their length or more, and the relatively large, pure white (rarely tinged pale pink) flowers with petals 15–20 mm long, the posterior two petals ± twice as wide as the anterior three.

Pelargonium crassipes and P. oreophilum from the Bokkeveld Mountains and Cederberg share similar, ± persistent petiole bases with P. conradiae but have smaller, pink to mauve flowers with darker markings on the posterior petals, and stipules that are adnate to the petioles for up to half their length only, becoming indurated and hook-like with age. P. oreophilum has characteristically narrow upper petals ± as wide as the anterior petals, and P.crassipes has deflexed, woody, strongly persistent, spine-like pedicels and stipules. P. hirtum , with consistently small flowers with petals ± 10 mm long, has herbaceous, scarcely persistent petioles, and often larger leaves, with blades and petioles mostly 20–50 mm long. All three of these species are fully illustrated in colour in Van der Walt (1977) and Van der Walt and Vorster (1981).

Distribution and ecology

A narrow endemic of the Breede River Valley southeast of Worcester in Western Cape Province, Pelargonium conradiae is known from two populations on the farms Drooge Riviersberg and Sandberg, and a third collection from the farm Alfalfa. Plants occur on the flats and lower slopes at the foot of spurs running out from the northern slopes of the Riviersonderend Mountains, in Succulent Karroo shrubland on clay and loamy clay soils derived from glacial tillite of the Dwyka Group of the Karoo Supergroup ( Gresse and Theron 1992). Annual rainfall rarely exceeds 250 mm. On the farms Drooge Riversberg and Sandberg, P. conradiae is associated with the rare Worcester endemic Annesorhiza radiata ( Apiaceae ) ( Magee et al. 2011) (see Fig. 3 ).

Conservation notes

Pelargonium conradiae was first collected on the farm Alfalfa in 1983 but additional populations have recently been found on the nearby farms Drooge Riviersberg and Sandberg. The species appears to be naturally rare, occurring in small groups numbering between three and ten individuals. Although the area is utilised for grazing (low intensity), the plants showed no signs of grazing. One of the stands of P. conradiae occurs partly under a transmission power line that runs through the area. Although Succulent Karoo vegetation is not fire-prone, management of power line servitudes by the South African national electricity supplier Eskom includes the periodic cutting of vegetation under such lines in order to ensure adequate access for maintenance as well as reduction of fuels for fires which may cause flashovers. Plants found in this area were smaller than the plants at undisturbed sites. It is uncertain how repeated cutting of the vegetation will affect the existence of P. conradiae . Additional specimens examined

South Africa. Western Cape: 3319 (Worcester): Farm Alfalfa , SE of Worcester, in karroid broken veld, flowers white, (− DA), 30 Aug. 1983 , D. Snijman 728 ( NBG); Farm Sandberg (− DC), 17 Aug. 2015, A . le Roux & H . Conradie 1405 ( NBG); 15 Aug. 2015, A . le Roux 1406 ( NBG) .

Figures

Fig.1. Pelargonium conradiae (Le Roux 1150, NBG).A,Floweringstems;B,detail ofpeduncular indumentum;C,detail offoliar indumentum;D,detached petals;E,androeciumspread out;F, gynoecium. Scale bar: A, D, 10 mm; B, C, 1 mm; E, F,5 mm.Artist: J.Manning.

Fig. 2. Pelargonium conradiae. A, Flowering plant in habitat; B, C, flowers showing unmarked, white petals; D,stems at end of dry season with emergent new growth and cartilaginous, semi-persistent stipules.Photographs:A.le Roux.

Fig. 3. Distribution of Pelargonium conradiae.