Thesium microcarpum A.DC.

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 : 299-300

5.2.2.5. Thesium microcarpum A.DC. in Esp. Nouv Thesium : 5 (1857a).

Thesidium microcarpum A.DC. in Flora 674 (1857a).

Thesidium exocarpaeoides Sond. in Flora 365 (1857b).

Type: South Africa. Western Cape, Cape Town (3318), Hessequas Kloof (-CD), without precise date, ♂ & ♀ plants Zeyher 3814 ( K, lectotype! designated here; BOL!, MO!, NBG!, OXF, PRE!, S!, isolectotypes) .

A brittle decumbent or suberect perennial suffrutex, 20–44 cm, usually growing beneath other shrubs, green to golden-green in overall appearance, rootstock slender. Stems woody at base, herbaceous at distal portion, 1–3 mm in diameter, sprawling; glabrous, terete in transverse section, branches decumbent, few at base but much-branched distally, 5–12 branches, leaves absent or rarely present on branchlets. Leaves scale-like, very few to almost absent, adpressed to branchlets, golden to yellowish green, tomentum glabrous, without a prominent venation or midrib, apex obtuse, margins fimbriate, straight. In fl orescence arranged along the branchlet, spicate, sessile on branchlets; bracts and bracteoles highly reduced to scales; bracts fleshy, 1–1.5 × 0.4–1 mm, triangular, margin entire, obtuse at tips, much shorter than flower length, incurved; bracteoles can easily be confused as bracts but bracteoles are closely adpressed to flowers, 0.8–1× 0.3–1 mm; flowers campanulate, white, 2–4 × 4–5 mm, 4-merous, external gland absent between perianth lobes; perianth lobe segments 2–3 × 1–3 mm, ovate, obtuse at tips, not distinctly uncinate, seldom lobulate, lobe tube inconspicuous, about 0.2 mm long. Male plant similar to female plants. Male plant: branches slender with dense branchlets distally, usually on a slen-der single stem; internodes 2–6.5 mm, leaves lax, not imbricate, ovate to triangular, 1–2 × 0.5–1 mm, inflorescences lax; hypanthium tube short to non-existent, shorter than perianth lobe tube; stamen tetramerous, corresponding to the lobe number, never pentamerous; staminal filaments exserted on the walls of perianth lobes at the junctions of the hypanthium tube, about 0.2 mm. Female plants: branches slender, fewer and stouter than male counterpart; internode 3.5–7.5 mm; leaves scanty, not imbricate, broadly ovate to triangular, 0.5–1.5 × 0.5–1 mm; inflorescences dense; hypanthium tube inconspicuous, shorter than perianth lobe tubes; style about 0.4 mm long. Fruit a nutlet, ovoid, white, elaiosome absent, 2–3 × 1–2 mm, without ribs or veins but surface tends to form wrinkles on drying, persistent perianth segment short relative to fruit length ( Fig. 9 ).

5.2.2.5.1. Diagnostic characters. Thesium microcarpum has been mistaken for T. fragile as both plants are brittle, have similar male and female counterparts, scale-like leaves, and white fruits. Thesium microcarpum differs from T. fragile in being decumbent or suberect, growing under other smaller shrubs (versus an erect, heath-like plant), branches mainly borne distally, inflorescences compacted on the branchlets, fruits ovoid, 5-ribbed with faint veins between veins, elaiosome absent (versus branches and inflorescences lax along stem length, fruit s truncated, without ribs or veins but surface wrinkles on drying, elaiosome present), usually found on shale, flat deep sand or sandstones (versus found on sand dunes, sandy soils and coastal sands).

5.2.2.5.2.Distribution and habitat. Thesium microcarpum has been collected widely across most of the GCFR extending from the Cedarberg Mountains of the Western Cape to Mannetjiesberg in the Eastern Cape ( Fig. 7C ). It occurs on shaley soil, well-drained stony soil, and deep sand to sandstone slopes in fynbos on gentle mountain slopes of the Cape Peninsula , in Rûens Shale Renosterveld vegetation types or in dry arid regions of the Karoo Mountains , usually under shrubby bushes at elevations, between 50 and 700 m above sea level.

5.2.2.5.3. Conservation status. Thesium microcarpum is a poorly studied taxon ( Von Staden, 2015), but is widely distributed across its local habitats and is abundant in nature reserves. Hence, we assessed it as Least Concern (LC), ( IUCN Standards and Petitions Subcommittee, 2017).

5.2.2.5.4. Additional materials studied. South Africa. EASTERN CAPE: 3326 (Grahamstown): Base of mountain at Rietvlei, along road to Mannetjiesberg (- BC), 10 Nov 2006, ♂ plants, Verboom 1149 ( BOL) . 3324 (Steytlerville): Plot 74, Baviaanskloof, north of Mountain top, above Enkeldoring (- CB), 20 Sep 2011, ♂ & ♀ plants, Euston-Brown 1256 ( NBG) .

WESTERN CAPE: 3218 (Clanwilliam): Rocherpan Nature Reserve, Relève 23, South end West of track (- CD), 22 Aug 1981, ♂ & ♀ plants, Rooyen & Ramsey 641 ( STE, NBG) . 3219 (Wuppertal): Cederberg mountains, Krakadouwsberg (- AA), 21 Sep 1963, ♀ plants, Stauffer 5190 ( BOL) . 3318 (Cape Town): Paardeberg, between Wellington and Malmesbury , Vlakfontein , (- DA), 24 Aug 2011, ♂ & ♀ plants, Nicolson & Roets 287 ( NBG) ; Dassenberg, middle of range, northern slope, Malmesbury (- DA), 11 Sep 1979, ♀ plants, Boucher 4701 ( NBG, STE) ; Helderfontein farm, Malmesbury (- DA), 11 Sep 1979, ♀ plants, Boucher 4441 ( NBG, STE) . 3319 (Swellendam): Rivierzondereinde, at Stormvallei , Hassaquaskloof and Breederivier (- CD), 01 Nov.1989, ♂ & ♀ plants, Zeyher 3814 ( HBG) . 3320 (Montagu): Dobbelarskloof, hillside, Montagu (- CC), 25 Sep 1946, ♀ plants, Lewis 3397 ( MO) ; near Barrydale, Swellendam (- CD), 05 Aug 1949, ♂ plants, Morris 171 ( NBG / BOL) ; Little Namaqualand Bend from Komaggas mountains (- DB), 02 Jul 1926, ♂ plants, Marloth 6950 ( STE) ; East of Anysberg West of Ladismith (- DA), 05 Oct 1982, ♀ plants, van Wyk 994 ( NBG, STE) ; Headlands along coastline, S of Pacaltsdorp, southern slopes of Rooiklip headlands (- DD), 14 Aug 1993, Victor 231 ( PRE) ; Montagu (- CD), 06 Oct 1993, ♂ & ♀ plants, Esterhuysen 37357 ( NBG) . 3321 (Ladismith): 2 miles on Port Elizabeth side of Schoenmaker-kop , (- AB), 30 Sep 1963, ♀ plants, Wells 2699 ( PRE) ; Klein Swartberg, ca. 1 km north of Seweweekspoort, near Ladismith (- AD), 26 Nov 2007, ♀ plants, Garcia, Gonzalez et al 3946 ( NBG) ; Touwsberg , W end summit ridge, on dry rocky slopes (- DB), 05 Oct 1993, ♂ & ♀ plants, Oliver 10319 ( STE, NBG) ; Klein Swartberg, just after turnoff for Rocklands, Towerkop Nature Reserve (- AD), 26 Nov 2007, ♀ plants, Garcia, Gonzalez et al 3947 ( NBG) . 3322 (Oudtshoorn): Ouhangsberg (- CC), 07 Nov 1992, Oliver 10260 ( STE) ; Boomplaas Cango valley , (- CB), 21 Jan 1976, ♀ plants, Hugo 8 ( BOL) ; Buffel rivier, below Kammanassieberg (- DB), 03 Oct 1971, ♂ plants, Thompson 1374 ( NBG, STE) . 3323 (Willowmore): Tsitzikamma mountains, Uniondale (- AD), 01 Mar 1950, ♂ & ♀ plants, Esterhuysen 16848 ( BOL) , Kammanassie, Uniondale (- AC), 31 Jan 1941, ♀ plants, Esterhuysen 4702 ( NBG / BOL) ; Buffelsberg, Kammanassie Mountains (- DB), 29 Oct 1983, ♂ plants, Viviers & Vlok 17 ( STE) . 3418 (Simonstown): Rooikrans, Fynbos Private Nature Reserve (- AA) , no precise date, Stirton 13844 ( BOL) . 3420 (Bredasdorp): Plaatjieskraal Farm, Overberg (- AA), 22 March 2017, ♂ and ♀ plant, Zhigila. & Muasya 149 ( BOL) ; Kykoedie Farm, 30 km from Bredasdorp to Stormsvlei (- AD), 01 Nov 2011, Stirton & Muasya 13, 434 ( BOL) ; Plaatjieskraal Farm, upper parts of Sonderkoskop , along jeep track and slopes in the reserve (- AD), 11 Sep 2017, ♂ and ♀ plant, Zhigila & Muasya 150 ( BOL) ; Nysti Farm, 40 km from Bredasdorp to Swellendam (- AD), 2 Nov 2011, ♀ plant, Stirton & Muasya 13445 ( BOL) ; De Hoop Nature Reserve, Windhoek (- AD), 17 Mar 1977, ♂ & ♀ plants, Thompson 3471 ( NBG, STE) . 3421 ( Riversdale ): hills near the Gouritz River (- CD) , no precise date, ♂ & ♀ plants, Schlechter 9433 ( K) ; Hills south of Vermaklikheid (- AC), 24 Nov 1972, ♂ & ♀ plants, Oliver, 4168 ( NBG, STE) ; On main road 2 km East of Resiesbaan siding (- AB), 28 Aug 1979, ♂ & ♀ plants, Bohnen 6242 ( NBG, STE) . 3422 ( Mossel Bay ): Groot Brak River, George Division (- CB), 08 Aug 1931, ♂ & ♀ plants, Thorne s.n. ( MO 51725 ) ; On trail near beach, above parking area, Knysna District, Goukama (- BB), 10 Jun 2008, Moore 52 ( NBG) ; Groot-Swartberg, along R314 ca 3.6 air km S of Klaarstroom, hills above rest area, at Peraboom Drif (- CD), 27 Nov 2007, ♂ & ♀ plants, García 3953 ( NBG) ; Boomplaas, Cango Valley (- AC), 29 Feb 1974, ♂ & ♀ plants, Moffett 302 ( NBG, STE) . 3423 (Knysna): along R340, ca. 8 km N of junction with N2, near Wittedrif (- AA), 04 Jun 2017, ♂ & ♀ plants, Zhigila 106 ( BOL) ; Noetsi River, W side (- AA), 22 May 1984, ♂ & ♀ plants, Callaghan & van Wyk 53 & 78 ( NBG, STE) .

Figures

Fig. 9. Thesium fruticulosum: (A) Plant habit on sandstone mountain fynbos, (B) male flowering shoot showing flower 4-merous and stamens, (C) fruiting female plants with short internodes,dense leaves, bracts and bracteoles longer relative to fruit length, (D) female plants showing flowering shoot, bract broken to display flower. 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 ▲.