Stemodiopsis buchananii Skan var. buchananii

Balkwill, K., 2020, A revision of Stemodiopsis Engl. (Linderniaceae) in South Africa, South African Journal of Botany 135, pp. 377-383 : 379-380

1 Stemodiopsis buchananii Skan var. buchananii

in Fl. trop. Afr. 4, 2: 315 316, excl. Buchanan 1220; Philcox in Fl. Zam. 8, 2: 40 (1990) pro parte; Fischer in Bot. Jahrb. Syst. 119, 3: 313 316 pro parte; Ghazanfar et al. in Fl. trop. E. Afr. Scrophulariaceae : 38 39 (2008).

Type: Malawi, without locality, 1891, Buchanan 365 ( K, Global Plants!, lecto. designated by Philcox, 1990) .

Perennial fruticose herb with woody base; glabrous, occasionally with very sparse scattered minute sessile glands on young stems and petioles, stems possibly deciduous, erect to pendent, up to 150 mm long. Leaves petiolate, blade ovate to elliptic, 5 15 X 3 9 mm, with (2) 3 or 4 (5) teeth on each side of the margin, apex acute or obtuse, base cuneate and decurrent on petiole; petiole 3 12 mm long. In fl orescences of axillary, single-flowered cymes, very rarely with a few 3- flowered cymes; peduncle 1.5 2.0 mm long; bracteoles linear-lanceolate, 1.2 1.5 X 0.4 0.5 mm; pedicel 2 3 mm long. Calyx glabrous, tube 0.3 0.5 mm deep, lobes lanceolate, 2 3 X 1.3 1.6 mm. Corolla tube white, 4.0 4.2 mm long, glabrous except for a few gland tipped hairs on outer surface at base of lobes; upper lip 1.6 2.0 X 2.0 mm, glabrous on inner surface; lower lip with short, broad, collapsing, ornamented trichomes on inner surface, with a distinct palate, lobes 2.0 X 2.5 mm, median lobe purple. Stamens didynamous, anterior (abaxial) filaments slightly curved at base, 3 mm long, anther 0.8 1.0 mm long, posterior (adaxial) filaments 2.1 2.5 mm long. Ovary 2 mm long, style 4 6 mm long. Capsule reflexed, 5.0 6.6 X 2.5 4.0 mm, glabrous. Seeds slightly curved, 1.2 X 0.4 mm.

Diagnostic characters: In South Africa, Stemodiopsis buchananii is characterised by its glabrous appearance ( Figs. 1A & B & 2A ), bearing at most sparse minute sessile glands ( Fig. 2C ), whereas most other species have hairs on the stem ( Fig. 2C & H ). The capsules of S. buchananii are glabrous ( Fig. 3A ), whereas those of other species are at least sparsely pubescent ( Fig. 3D G ). Other taxa that share these characters have cymes with more than one flower, whereas S. buchananii has most cymes with only a single flower.

Taxonomic notes: Only var. buchananii occurs in South Africa. Stemodiopsis buchananii var. pubescens Philcox is characterised by having dense short, broad, ornamented trichomes on the stem, particularly when they are young ( Figs. 2B & E ) and it has so far only been collected in the Chimanimani Mountains.

Etymology: Named for collector of the type, Reverend John Buchanan (1855 1896) a Companion of the Order of St Michael and St George (C.M.G.), who was a, horticulturist, missionary and British vice-consul for the Lake Malawi region ( Kalinga, 2012). He collected over 2 000 specimens mainly in Malawi and major holdings of his specimens are at B, BM and K ( Stafleu and Mennega, 1995).

Distribution and ecology: Stemodiopsis buchananii is one of the more widespread species in the genus, occurring from Sudan and Somalia southwards to Swaziland. In tropical Africa, several taxa are currently treated under this name, but even with those segregated, the species will be widespread. In South Africa, S. buchananii occurs in Limpopo and Mpumalanga and it occurs in Swaziland ( Fig. 3 ). The species occurs in crevices on boulders and cliff faces.

Phenology: In South Africa, S. buchananii has been collected in flower and fruit from December through to May.

Conservation notes: This is a widespread species and although the habitat is very specific, it is not threatened by many activities. Least Concern (LC), as recorded by Ghazanfar et al. (2008), is endorsed.

Additional specimens examined:

South Africa. LIMPOPO. 2330 (Tzaneen): About 30 km north of Graskop, on border of Goedgeloof and Erasmushoop , near Treur River , 1850 m (DB), 20 Mar 1993, Cron, Balkwill & Balkwill 252 ( J). MPUMALANGA. 2430 (Pilgrim’ s Rest): Blyderivierspoort Nature Reserve, below Bohlabapeba , 1289 m (DB), 21 May 2001, Balkwill et al. 12,098 ( J, K). 2527 (Rustenburg): Magaliesberg , Rietvlei , Snapdragon Krantz (CA), 15 Oct 1943, Rose-Innes 204 ( J). Swaziland. 2632 (Bela Vista): Lubombo Mountains , 26° 13 ' S, 32° 4 ' E, 400 m (AA), 3 Dec 1978, Kemp 1471 ( PRE); Blue Jay Ranch, below farmhouse, 4.8 km NNW of Mhlumeni border post , 445 m (AA), 12 Nov 1977, Culverwell 1176 ( PRE); 700 m SSE of old farmhouse , 400 m (AA), 4 Feb 2008, Burrows 10,364 ( BNRH).

Figures

Fig. 1. Habit of: A, B, Stemodiopsis buchananii var. buchananii; C, D, S. kamundii.Photographers: A, Troos van der Merw in iNaturalist; B. Bart Wursten in Flora of Zimbabwe; C, Delia Oosthuizen; D, Nick Helme in iNaturalist

Fig. 2. Indumentum on stems of: A, D, Stemodiopsis buchananii var. buchananii, voucher Cron et al. 252 (J); B, E, S.buchananii var. pubescens, voucher Grosvenor 327 (SRGH); C, F, S. kamundii, voucher Balkwill & Balkwill 8262 (J); G, S. kamundii, voucher van der Schijff 3571 (PRE); H, I, S. rivae, voucher Pawek 12,752 (MO). Scale bars = 0.5 mm for A‒C & G‒H and 0.1 for D‒F & I.

Fig. 3. Indumentum on fruits of: A, Stemodiopsis buchananii var. buchananii, voucher Cron et al. 252 (J); B, S. buchananii var. pubescens, voucher Grosvenor 327 (SRGH); C, S. rivae, voucher Pawek 12,752 (MO); D, E, S. kamundii, voucher Balkwill & Balkwill 8262 (J); F, G, S. kamundii, voucher van der Schijff 3571 (PRE).Scale bars = 1 mm for A‒D & G and 0.2 mm for D & E.