Thesium fruticulosum (A.W.Hill) J.C.Manning & F.Forest

Zhigila, D. A., Verboom, G. A., Stirton, C. H. & Muasya, A. M., 2019, A taxonomic revision of Thesium section Hagnothesium (Santalaceae) and description of a new species, T. quartzicolum *, South African Journal of Botany 124, pp. 280-303 : 292-295

5.2.2.2. Thesium fruticulosum (A.W.Hill) J.C.Manning & F.Forest in Bothalia 43(2): 215 (2013).

Thesidium fruticulosum A.W.Hill in Bull. Misc. Inform. Kew 3: 98 (1915); A.W. Hill in Fl. Cap. 5(2): 205 (1925).

Type: South Africa. Western Cape, Caledon (3420AB): Vogelgat, Austro-Africanae. Regio occidentalis . Vogelgat, 11 Apr 1897, Schlechter 10414 ♂ and ♀ 10415 (L, lectotype, designated here; BOL!, HBG!, K!, NBG!, PRE! isolectotypes).

The assignment of Schlechter 10414 as lectotype is supported by its locality within the typical geographical range of the species and is one of the six specimens cited by Hill (1925) and that has both male and female plants on the same sheet.

An erect or spreading perennial suffrutex, to about 30 cm tall, heath-like or growing beneath other shrubs, golden green in appearance, plant not brittle, woody taproot or slender rootstock, branched mainly from basal part, 5–15 branches, branching pattern fastigiate, leaves subtending each branchlet. Stems woody at base, herbaceous above, 2.0– 3.5 mm in diameter, erect or suberect, glabrous to subglabrous, terete in transverse section. Leaves well developed, erect to adpressed to the stem, green basally but turning golden toward the attenuate tips, glabrous and glossy, without prominent venation or midrib, apex acute, margins entire, concavely recurved, rarely straight. In fl orescences arranged along the branch length, in branchlet axils, in spikes, attached to the stem by a short or no pedicel; bracts and bracteoles leaf-like; bracts fleshy, 2–6 × 1–2 mm, linear-lanceolate, margins conspicuously ciliated, membranous, golden green particularly toward the basal part, acute at tips, much longer than the flower, incurved; bracteoles bract-like but smaller, 2–4 × 0.7–2 mm. Flowers campanulate, golden green, 1–2.5 × 0.8–1.5 mm, 4-merous, external gland between perianth lobes absent; perianth lobe segments 0.5–1.2 × 0.5–0.8 mm, lobes ovate to triangular, obtuse or subacute at tips, neither distinctly uncinate nor lobulate; tube ca. 0.5 mm. Male and female plants well differentiated. Male plant: branches more slender than female counterparts, internodes 0.5–4 mm long; leaves dense, almost imbricate, more slender than female leaves, linear-lanceolate, 3–6 × 0.5–1.5 mm; inflorescences lax; hypanthium tube shallow; stamen tetramerous, staminal filaments exserted at the junction of hypanthium and perianth lobe tubes, about 0.3 mm long. Female plant: branches more robust, internodes as short as the male counterpart, 0.5–3.6 mm; leaves dense, imbricate, linear, 10–11 × 1–1.5 mm. inflorescences lax; hypanthium tube length less than the perianth lobe tubes; style stout, about 0.3 mm long. Fruit a nutlet, ovoid, green, attached to the branch by white attenuated elaiosome, 1.5–3 × 1–2.5 mm, with 10 conspicuous ribs, rarely 5, with prominent venation connecting the ridges particularly when dry, capped with green persistent perianth lobe segments, shorter relative to the fruit length ( Fig. 11 ).

5.2.2.2.1. Diagnostic characters. T. fruticulosum is similar to T. minus in their glabrous parts, terete stems, fastigiate branching habit mainly from the base, linear leaves, 3–10 cm long, midrib not raised, and bracts and bracteoles leaf-like. T. fruticulosum is a 15–30 cm tall, perennial suffrutex with a woody taproot system, absent rhizome stem (versus a 5–10 cm tall, annual herb with a fibrous perennial root system, and rhizome stem present), internodes 0.5–3 mm in female plants (versus 3–8.5 mm), leaves in both male and female similar (versus leaves smaller in males than females) and fruits consistently with elaiosomes (versus with or without elaiosomes).

5.2.2.2.2. Distribution and habitat. Although T. fruticulosum has a widespread distribution, it is poorly collected from Soebatsfontein to Brandberg in the Northern Cape, and from the coastal and mountain fynbos of the Western Cape and eastwards to Grahamstown in the Eastern Cape ( Fig. 7B ). It occurs in mountain fynbos-renosterveld and the drier areas of Succulent Karoo favouring sandstone flats and mountain flanks, rich as well as the nutrient-poor rocky soil across the GCFR from sea level to about 1500 m a.s.l. It has been collected on coastal beach sands, deep sandy flats and sandstone mountain slopes across the southwest in the Western Cape to southeast in the Eastern Cape ( Manning and Goldblatt, 2012). It also occurs in mountain fynbos, shale renosterveld and on gentle slopes of forest edges in the Kogelberg State Forest, Southern Hottentots Holland Mountains, Langeberg and the upper slopes of the Swartberg Mountains.

5.2.2.2.3. Conservation status. Since T. fruticulosum is abundant across its geographical range, von Staden (2015) assessed it as LC (least concern). Our data support this assessment.

5.2.2.2.4. Additional specimens studied. South Africa NORTHERN CAPE: 2917 ( Namaqualand ): 4.7 km W of Komaggas-Soebatsfontein road to Brandberg (- CD) , on well drained sandy soil, 20 Oct 1986, ♂ & ♀ plants, le Roux & Lloyd 732 ( STE) . 3119 ( Calvinia ): without precise locality, (- BC) , 1969, ♂ & ♀ plants, Heinecken 233 ( BOL) .

EASTERN CAPE: 3324 (Steytlerville): St. Francis Bay (- BC), 02 Feb 1961, ♀ plants, Levyns 11124 ( BOL) .

WESTERN CAPE: 3218 ( Clanwilliam ): 9.5 mi SW of Redelinghuys, Piketberg (- AD), 25 Aug 1958, Acocks 19, 698 ( PRE) . 3318 ( Cape Town ): Wynberg coastal hill slopes (- AB), 28 Nov 1897, ♂ & ♀ plants, Galpin 4556 ( BOL) . 3418 ( Simonstown ): Dias beacon ridge, Simonstown, (- BD), 18 Dec 1965, Taylor 6629 ( STE) ; Cleared slope, Kirstenbosch (- AB), 26 Oct 1936, ♂ & ♀ plants, Levyns 5908 ( BOL) ; Southern Hottentots Holland Mountains, Kogelberg State Forest (- BD), 27 Oct 1992, ♀ plants, Kruger 857 ( NBG, STE) . 3419 ( Caledon ): Betty's Bay Nature Reserve (- AA), 01 Aug 1963, ♂ & ♀ plants, Stauffer 5053 ( BOL) ; Along R321, 7.2 km NE of Grabouw and N2 (- AA), 15 Dec 2007, ♂ & ♀ plants, García & Lopez 4058 ( NBG) ; Vogelgat , above Dragonfly Pool (- AD), 01 Apr 1897, ♀ plants, Williams 3794 ( BOL) ; Rietfontein Nature Reserve , western point of Soetanysberg (- DD), 23 Mar 1982, ♂ plants, van Wyk 806 ( NBG, STE) ; North west Buffeljagtsberg (- DA), 11 Mar 1979, ♂ plants, Thompson 3946 ( NBG, STE) ; Fernskloof Nature Reserve , Hermanus (- AB), 24 Aug 2018, ♀ plants, Zhigila 267 ( BOL, K, NBG) ; ♂ & ♀ plants, Zhigila 268 ( BOL, K, NBG) . 3420 ( Bredasdorp ): Hagel Kraal, limestone hill, (- BC), 28 Dec 1946, Compton 19039 ( NBG) . 3422 ( Mossel Bay ): Goukamma National Reserve (- BB) , without specific date, ♀ plants, Heinecken 266 ( BOL) ; Goukamma (- BB), 01 Dec 1971, ♂ & C, Heinecken 267 ( PRE) ; Hills S of Buffalo Bay (- CD), 01 Dec 1928, ♂ & ♀ plants, Salter 318/3 ( BOL) .

Figures

Fig. 11. Thesium longicaule: (A) habit and substrate of female plants, (B) habit of male plant based on Bolus 4608 (K!), (C) male flowering shoot, (D) detailed male flowering shoot, (E) female fruiting shoot. Photographs: Daniel Zhigila.

Fig. 7. Distribution of species of Thesium section Hagnothesium: (A) T.fragile, (B) T.fruticulosum, (C) T.microcarpum, (D) T.minus, (E).T.hirtum •, T.quartzicolum ▲, (F) T.leptostachyum •, T. longicaule ▲.