1. Family: Santalaceae R.Br.
    1. Genus: Thesium L.
      1. Thesium nigricans Rendle

        This species is accepted, and its native range is S. TropicalAfrica.

    [FZ]

    Flora Zambesiaca. Vol. 9, Part 3. Polygonaceae-Myriaceae. Pope GV, Polhill RM, Martins ES. 2006.

    Type
    Lectotype, chosen here: Malawi, Mt. Mulanje, c. 1800 m, x.1891, Whyte 42 (BM, lectotype; K).
    Stamens
    Stamens inserted at base of lobes; filaments 0.2–0.8 (0.2–0.3) mm long, clearly visible; anthers 0.25–0.5 (0.25–0.3) mm Stamens inserted at base of lobes; filaments 0.2–0.8 (0.2–0.3) mm long, clearly visible; anthers 0.25–0.5 (0.25–0.3) mm.
    Style
    Style 0.5–1.8 (0.4–0.6) mm long; stigma reaching top of anthers
    Fruits
    Fruit 1.8–2.5 × 1.7–2.5 mm, light yellowish- to red-brown, with ribs and reticulations, but these not strongly raised. Fruit 1.8–2.5 × 1.7–2.5 mm, light yellowish- to red-brown, with ribs and reticulations, but these not strongly raised.
    Ecology
    Rocky montane scrub and forest patches, also Brachystegia ‘miombo’ woodland, locally common; c. 1200–2500 m in Zimbabwe and Mozambique (though possibly confined to summit of Gorongosa Mts. at c. 1850 m), Mt. Mulanje above c. 1850 m. Apparently confined to Mulanje and Zomba Mts. in Malawi, the mountains of eastern Zimbabwe from Nyanga (Inyanga) to the Chimanimani Mts. and neighbouring heights in Mozambique, including Gorongosa Mt.
    Note
    On Gorongosa, flowers tend to be smaller than elsewhere; the measurements are given in parentheses in the formal description above. Thesium nigricans is closely allied to T. kilimandscharicum: they are similar in the ribbing of the stems, leaf characters and inflorescence, but T. kilimandscharicum consistently has a 3–4-merous perianth with an exceptionally short tube completely obscured inside by the thick disk, and a very short style, in contrast to the predominantly 5-merous perianth of T. nigricans, with a well developed tube and longer style. Also, T. kilimandscharicum appears to be annual as it has only a slender taproot, whereas T. nigricans is perennial, with a stout woody caudex. Plants from the environs of Chimanimani (type locality for T. scabridulum) are mostly scabridulous, sometimes markedly so, but elsewhere there are all degrees of development of these tiny projections, even on a single specimen; the type material of T. nigricans is very weakly scabridulous. Differences in facies are induced by the degree of crowding of the leaves and variation in their size. In general, the distinguishing characters of T. nigricans (in addition to its drying black or at least dark and its glabrous perianth lobes) are its profusely branched stems resulting in great leafy panicles of twiglets terminating in 1–6-flowered racemes, and the distinctive ribbing of the stems.
    Distribution
    Mozambique Malawi ZIM E, MAL S, MOZ MS Zimbabwe
    Habit
    Perennial herb with small woody caudex; stems few to many from the crown, c. 300 mm–1 m tall, erect, decumbent or straggling, profusely divaricately branched, broadly ribbed by the decurrent leaves, distinctly channelled between the ribs (when dry, ribs blackish to dark red-brown, channels paler), leafy, whole plant drying black to dark red-brown. Perennial herb with small woody caudex; stems few to many from the crown, c. 300 mm–1 m tall, erect, decumbent or straggling, profusely divaricately branched, broadly ribbed by the decurrent leaves, distinctly channelled between the ribs (when dry, ribs blackish to dark red-brown, channels paler), leafy, whole plant drying black to dark red-brown
    Leaves
    Leaves ascending-recurved to spreading, c. 7–20 × 0.5–1 mm, smaller upwards and passing into bracts, linear, apiculate, margins cartilaginous, smooth to very minutely scabridulous, scabrid projections sometimes dorsal as well and extending down the stems on the decurrent leaves, ventral surface flat, dorsal ± rounded (leaf deltoid in section). Leaves ascending-recurved to spreading, c. 7–20 × 0.5–1 mm, smaller upwards and passing into bracts, linear, apiculate, margins cartilaginous, smooth to very minutely scabridulous, scabrid projections sometimes dorsal as well and extending down the stems on the decurrent leaves, ventral surface flat, dorsal ± rounded (leaf deltoid in section)
    Flowers
    Flowers solitary in axils of bracts, 1–6 racemosely arranged at branchlet tips, the whole forming a profusely branched panicle. Flowers solitary in axils of bracts, 1–6 racemosely arranged at branchlet tips, the whole forming a profusely branched panicle
    Bracts
    Bracts (lowermost) 3–12.5 × 0.4–1.1 mm, linear, leaf-like, adnate almost or quite to entire pedicel; bracteoles 2, similar to bracts but smaller. Bracts (lowermost) 3–12.5 × 0.4–1.1 mm, linear, leaf-like, adnate almost or quite to entire pedicel; bracteoles 2, similar to bracts but smaller
    Pedicel
    Pedicels 0.5–3 mm long, or flowers sessile. Pedicels 0.5–3 mm long, or flowers sessile
    Perianth
    Perianth pale yellowish-green to whitish; tube 0.5–1.2 (0.4–0.5) mm long, external glands inconspicuous; lobes 0.7–1.5 × 0.5–0.8 (0.7–0.8 × 0.4–0.6) mm, usually 5, occasionally 4 and then mixed with 5-lobed flowers, triangular, subacute, glabrous. Perianth pale yellowish-green to whitish; tube 0.5–1.2 (0.4–0.5) mm long, external glands inconspicuous; lobes 0.7–1.5 × 0.5–0.8 (0.7–0.8 × 0.4–0.6) mm, usually 5, occasionally 4 and then mixed with 5-lobed flowers, triangular, subacute, glabrous
    Pistil
    Style 0.5–1.8 (0.4–0.6) mm long; stigma reaching top of anthers.

    Images

    Distribution

    Native to:

    Malawi, Mozambique, Zimbabwe

    Thesium nigricans Rendle appears in other Kew resources:

    Date Reference Identified As Barcode Type Status
    Jan 1, 1989 Synnerton, C.F.M. [2124], Zimbabwe K000431488 Unknown type material
    Whyte, A. [42], Malawi K000431487 Unknown type material
    Synnerton, C.F.M. [2124], Zimbabwe K000431489 Unknown type material

    First published in Trans. Linn. Soc. London, Bot. 4: 41 (1894)

    Accepted by

    • Pope, G.V., Polhill, R.M. & Martins, E.S. (eds.) (2006). Flora Zambesiaca 9(3): 1-277. Royal Botanic Gardens, Kew.

    Literature

    Flora Zambesiaca
    • F.T.A. 6, 1: 424 (1911). TAB. 45, fig. C.
    • Trans. Linn. Soc., London, Bot. 4: 41 (1894).
    Kew Backbone Distributions
    • Pope, G.V., Polhill, R.M. & Martins, E.S. (eds.) (2006). Flora Zambesiaca 9(3): 1-277. Royal Botanic Gardens, Kew.

    Sources

    Flora Zambesiaca
    Flora Zambesiaca
    http://creativecommons.org/licenses/by-nc-sa/3.0

    Herbarium Catalogue Specimens
    'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.
    Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

    Kew Backbone Distributions
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Names and Taxonomic Backbone
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0