1. Family: Santalaceae R.Br.
    1. Genus: Thesium L.
      1. Thesium atrum A.W.Hill

        This species is accepted, and its native range is S. DR Congo to S. Tropical Africa.

    [FZ]

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

    Type
    Type from Angola.
    Habit
    Perennial herb drying black, with a woody caudex c. 15–25 mm in diameter crowned with very many short closely scaly shoots eventually elongating into stems c. 150–450 mm long, 1.5–5 mm diameter at base, erect or possibly decumbent or ascending, fastigiately well branched from the base or a little higher, branches irregularly racemose-cymose, ascending at angle of c. 45° or sometimes almost at right angles, minutely ciliolate to glabrous (cilia up to c. 0.2 mm long developed particularly near base, present or absent even in one collection), very shallowly ribbed by decurrent scales Perennial herb drying black, with a woody caudex c. 15–25 mm in diameter crowned with very many short closely scaly shoots eventually elongating into stems c. 150–450 mm long, 1.5–5 mm diameter at base, erect or possibly decumbent or ascending, fastigiately well branched from the base or a little higher, branches irregularly racemose-cymose, ascending at angle of c. 45° or sometimes almost at right angles, minutely ciliolate to glabrous (cilia up to c. 0.2 mm long developed particularly near base, present or absent even in one collection), very shallowly ribbed by decurrent scales.
    Leaves
    Leaves all reduced to scales, the largest subtending primary branches c. 1.2–4 × 0.8–1.2 mm, lanceolate to ovate-lanceolate, cuspidate, thick-textured, margins usually ciliolate Leaves all reduced to scales, the largest subtending primary branches c. 1.2–4 × 0.8–1.2 mm, lanceolate to ovate-lanceolate, cuspidate, thick-textured, margins usually ciliolate.
    Flowers
    Flowers solitary terminating scaly or nude shoots arranged in two ways: either first shoot from each leaf (scale) on main stem scaly, thereafter fastigiately branched, the branchlets mostly with a very short (c. 1–10 mm long) scaly brachyblast arising in each axil and terminating in a flower or the branching irregularly cymose, the primary peduncle nude, subsequent branches both scaly and nude Flowers solitary terminating scaly or nude shoots arranged in two ways: either first shoot from each leaf (scale) on main stem scaly, thereafter fastigiately branched, the branchlets mostly with a very short (c. 1–10 mm long) scaly brachyblast arising in each axil and terminating in a flower or the branching irregularly cymose, the primary peduncle nude, subsequent branches both scaly and nude.
    Bracts
    Bracts c. 5 forming an involucre below the flower, 0.8–1.8 × 0.5–1 mm, ovate-cuspidate, margins ciliolate Bracts c. 5 forming an involucre below the flower, 0.8–1.8 × 0.5–1 mm, ovate-cuspidate, margins ciliolate.
    Pedicel
    Pedicels wanting Pedicels wanting.
    Perianth
    Perianth “creamy-green”; tube 0.6–1 mm long, external ellipsoid glands very obscure; lobes 1–1.5 × 0.4–0.7 mm, oblong-lanceolate, subacute, hood 0.3 mm long, margins inflexed, erose Perianth “creamy-green”; tube 0.6–1 mm long, external ellipsoid glands very obscure; lobes 1–1.5 × 0.4–0.7 mm, oblong-lanceolate, subacute, hood 0.3 mm long, margins inflexed, erose.
    Stamens
    Stamens inserted at base of perianth lobes; filaments 0.25–0.4 mm long, ± hidden by anthers; anthers 0.3–0.6 mm long Stamens inserted at base of perianth lobes; filaments 0.25–0.4 mm long, ± hidden by anthers; anthers 0.3–0.6 mm long.
    Style
    Style 1.2–1.7 mm long; stigma reaching ± to tip of hood
    Ecology
    Mixed woodland on Kalahari Sands and in sandy grassland; c. 900–1400 m.
    Note
    The type of T. atrum came from the Luassinga R. (not Suassingua as given in F.T.A. 6) in Angola, roughly 400 km west of the Zambian border. The type of T. quarrei (in synonymy above) came from Katuba in Shaba (Haut-Katanga) and it is precisely matched by Phipps 849 (quoted above) from a site in Zimbabwe roughly 750 km to the SE. So despite the paucity of specimens available for study, it is clear that the species has a wide distribution. The leaves of T. atrum are all reduced to scales, the largest usually c. 1.2–3.5 × 0.8–1.2 mm; the longest (and narrowest in relation to length viz. 4 × 0.8 mm) leaves occur on a tiny basal shoot on the type of T. quarrei; the leaves on the main stems resemble those on the rest of the material.
    Distribution
    Also in Angola and Katanga (Shaba) Province of Dem. Rep. Congo. Zimbabwe ZAM B, ZAM S, ZIM N Zambia
    Pistil
    Style 1.2–1.7 mm long; stigma reaching ± to tip of hood.
    Fruits
    Fruit 2.5–3 × 2.5 mm, drying black, strongly ribbed and reticulate. Fruit 2.5–3 × 2.5 mm, drying black, strongly ribbed and reticulate.

    Images

    Distribution

    Native to:

    Angola, Zambia, Zaïre, Zimbabwe

    Thesium atrum A.W.Hill appears in other Kew resources:

    Date Reference Identified As Barcode Type Status
    Gossweiler [2713], Angola K000431509 Unknown type material

    First published in Bull. Misc. Inform. Kew 1910: 182 (1910)

    Accepted by

    • Figueiredo, E. & Smith, G.F. (2008). Plants of Angola Strelitzia 22: 1-279. National Botanical Institute, Pretoria.
    • 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: 430 (1911).
    • Bull. Misc. Inform., Kew 1910: 182 (1910).
    Kew Backbone Distributions
    • Figueiredo, E. & Smith, G.F. (2008). Plants of Angola Strelitzia 22: 1-279. National Botanical Institute, Pretoria.
    • Pope, G.V., Polhill, R.M. & Martins, E.S. (eds.) (2006). Flora Zambesiaca 9(3): 1-277. Royal Botanic Gardens, Kew.
    • Robyns, W. & al. (eds.) (1948-1963). Flore du Congo Belge et du Ruanda-Urundi 1-10.

    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