Thesium brevibarbatum Pilg.

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

Type

Type:Zimbabwe, grassy steppe near Mutare (Umtali), 1200 m, ix.1905, Engler 3176 (B†, holotype; K, fragment).

Morphology Leaves

Leaves ascending, c. 5–13 × 0.6–1.2 mm, those at base of stem often reduced, linear, apex apiculate, base broad, thick-textured, margins pale, cartilaginous, minutely scabridulous, midrib slightly raised on both surfaces, minutely scabridulous on dorsal face Leaves ascending, c. 5–13 × 0.6–1.2 mm, those at base of stem often reduced, linear, apex apiculate, base broad, thick-textured, margins pale, cartilaginous, minutely scabridulous, midrib slightly raised on both surfaces, minutely scabridulous on dorsal face.

Morphology Reproductive morphology Flowers

Flowers mostly solitary, occasionally paired or in a 3-flowered cymule, up to c. 10 racemosely arranged at tips of branchlets, often crowded Flowers mostly solitary, occasionally paired or in a 3-flowered cymule, up to c. 10 racemosely arranged at tips of branchlets, often crowded.

Morphology Reproductive morphology Inflorescences Bracts

Bracts c. 5–14 × 0.8–1.5 mm, linear, leaf-like, adnate to part of pedicel/peduncle (often only to lower quarter or half, higher in uppermost flowers); bracteoles 2, c. 3–1 × 0.5–1 mm Bracts c. 5–14 × 0.8–1.5 mm, linear, leaf-like, adnate to part of pedicel/peduncle (often only to lower quarter or half, higher in uppermost flowers); bracteoles 2, c. 3–1 × 0.5–1 mm.

Morphology Reproductive morphology Inflorescences Peduncles

Peduncles (lowermost) up to 6 mm long, but often only half that Peduncles (lowermost) up to 6 mm long, but often only half that.

Morphology Reproductive morphology Flowers Perianth

Perianth colour unknown; tube 0.5–1 mm long, external glands ellipsoid, equalling tube; lobes 1–1.5 × 0.6–0.8 mm, triangular, acute, white-bearded from apex Perianth colour unknown; tube 0.5–1 mm long, external glands ellipsoid, equalling tube; lobes 1–1.5 × 0.6–0.8 mm, triangular, acute, white-bearded from apex.

Morphology Reproductive morphology Flowers Gynoecium Style

Style 0.5–1 mm long; stigma reaching about halfway up anthers

Ecology

Brachystegia woodland; 900–1700 m.

Note

The holotype of T. brevibarbatum was destroyed in the disastrous Berlin fire; a few fragments are preserved in the Kew Herbarium, the largest piece being an entire stem 90 mm long, in flower but not in fruit. Similar short flowering stems are present on all three of the collections cited above, and which constitute all the material seen by me. In two of these specimens, collected between the end of November and the end of December, these short stems are well past flowering (they bear only the persistent bracts and bracteoles) and are overtopped by younger, laxer flowering branches; the third specimen (Mavi 768) collected in mid-August, is only in the first stage of flowering. It seems likely that these short primary flowering stems are characteristic of the species, and will distinguish it from its close (and sympatric) ally, T. gracile, which shows no trace of them, and seems to flower only when it attains a height of at least 150 mm. Furthermore, the flowers of T. brevibarbatum are mostly borne singly in the axil of each bract; in T. gracile, they are mostly in 3-flowered cymules.

Distribution

Possibly confined to the eastern half of Zimbabwe and nearby parts of Mozambique. Mozambique ZIM C, ZIM E, MOZ MS Zimbabwe

Morphology General Habit

Perennial herb with a small woody and somewhat stoloniferous caudex; stems many, tufted from the crown, 70–200 mm long, well branched from the base, shallowly ribbed, leafy. Perennial herb with a small woody and somewhat stoloniferous caudex; stems many, tufted from the crown, 70–200 mm long, well branched from the base, shallowly ribbed, leafy

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens inserted at base of lobes; filaments 0.3–0.5 mm long, almost hidden by anthers; anthers 0.4–0.6 mm long. Stamens inserted at base of lobes; filaments 0.3–0.5 mm long, almost hidden by anthers; anthers 0.4–0.6 mm long

Morphology Reproductive morphology Flowers Gynoecium Pistil

Style 0.5–1 mm long; stigma reaching about halfway up anthers.

Morphology Reproductive morphology Fruits

Fruit c. 3 × 3 mm, pallid, strongly ribbed and reticulate. Fruit c. 3 × 3 mm, pallid, strongly ribbed and reticulate.