Stachys pseudonigricans Gürke

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: not threatened. Confidence: confident

J. R. Timberlake, E. S. Martins (2013). Flora Zambesiaca, Vol 8: part 8. Royal Botanic Gardens, Kew

Type

Type: Malawi, Shire Highlands, ii.1881, Buchanan 28 (K holotype).

Morphology General Habit

Perennial erect or procumbent, lax or bushy herb, 0.15–0.8(1) m tall, faintly aromatic- Stems quadrangular to rounded, branching throughout length, densely to laxly covered with a combination of dendroid, stellate and/or biramous (occasionally simple) hairs

Morphology Leaves

Leaves sessile or petiolate, (12)24–80(130) × (1.5)5–38(45) mm, narrowly to broadly lanceolate, broadly ovate, sometimes more than one leaf-shape per plant, apex acute to acuminate or rounded, base rounded to truncate, margin crenate to laxly toothed, laxly to densely pubescent, upper and lower surface with simple biramous, stellate and/or dendroid hairs; petiole 1–10 mm long, laxly to densely pubescent

Morphology Reproductive morphology Inflorescences

Inflorescence lax; verticils (2)4–10(13) per stem, (4)6–8(16)-flowered, 5–70(105) mm apart; bract 4–90 × 1–28 mm, similar to cauline leaf, pubescent; bracteoles 1–8(12) mm long, narrowly linear; pedicel (0.5)1–4 mm long, pubescent

Morphology Reproductive morphology Flowers Calyx

Calyx 5.5–13 mm long at anthesis, extending to 16 mm long in fruit, ascending, funnel campanulate, outer surface pubescent, glabrous within, broadening in fruit; teeth 5, (1.5)2–4(7) mm long, narrowly triangular, apex acuminate, erect to recurved

Morphology Reproductive morphology Flowers Corolla

Corolla 9–16 mm long, white to pink to pale lavender/mauve, with or without darker flecks; tube (5)6–10 mm long, straight, ± shorter than calyx, outer surface ± glabrous, glabrous within except for band of hairs at midpoint of tube, pubescent at apex; lower lip 3.5–8 mm long, outer surface pubescent, glabrous within; upper lip 2–5(6) mm long, outer surface densely pubescent

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens held under upper lip, filaments pubescent, all adnate to corolla above midpoint of tube; anther 2-locular, divaricate

Morphology Reproductive morphology Flowers Gynoecium Style

Style bifid; disk 4-lobed, margin ciliate

Morphology Reproductive morphology Fruits

Nutlets dark brown, 1.5–3 mm long, broadly ovoid, minutely tuberculate, pubescent at apex when immature, glabrous when mature.

Distribution

Zambia, Zimbabwe, Malawi, Mozambique. Also in Tanzania and Angola.

Ecology

Grassland, bushland, wetlands and miombo woodland; 600–1800 m.

Conservation

Widespread; Least Concern.

Recognition

Stachys pseudonigricans is a polymorphic species comprising a central type from which four morphological extremes radiate, each with intermediates. The type form and three of the groups are petiolate with dendroid and stellate hairs; the remaining group has biramous and stellate hairs and ± sessile leaves. The description above is based on all material of S. pseudonigricans, but may be misleading when comparing material from just the Flora Zambesiaca area that comprises the type form and intermediates between extreme forms found in the Southern Highlands of Tanzania. The type form has lanceolate leaves (24–80 × 5–38 mm) throughout the plant which are laxly pubescent with simple biramous, stellate and/or dendroid hairs on the upper and lower surfaces, an acute apex and rounded to truncate base; the stems have lax dendroid, dendroid and stellate and occasionally stellate pubesence. Most leaves are petiolate (1–10 mm long) but are occasionally sessile. There are 6–12 flowers per verticil; bracteoles 1–8 mm long; corolla 9–16 mm long, white to pink to pale lavender/mauve in colour (with or without darker flecks). It is known from Malawi (Shire Highlands, Chitipa, Nkhata Bay, Mzimba and Rumphi districts), The remaining group tends to have much narrower leaves with indumentum that lacks dendroid hairs. There are two extremes, one with tall plants with very narrow leaves and another comprising shorter plants with narrow leaves and distinctly long bracts at the branch apex. The taller of the extremes is found in Tanzania (Rungwe, Mbosi and Mbeya districts), an intermediate type with pronounced leaf differences is found in Tanzania (Mbeya Dist.) and Malawi (Chitipa and Rungwe districts), while another intermediate type without leaf differences is known from Tanzania (Mpanda, Mbeya, Nkansi and Songea districts), Malawi (Nyika Dist.) and Zambia (Chati, Ndola and Kitwe districts). The type form has simple biramous, stellate and/or dendroid hairs, so the last group cannot be separated from the other forms for lacking dendroid hairs. All extremes have intermediates linking them to the type form and so cannot be placed in separate taxa. The second group with dendroid hairs are large plants with ovate-lanceolate leaves. Intermediates are as large but have more lanceolate leaves. The extreme form is known from Tanzania (Mufindi, Iringa and Sumbawanga districts) with intermediates from Mbeya, Lupa, Nkansi and Sumbawanga districts in Tanzania, and Mongu, Mazabuka, Kalambo Falls and Chilongowelo in Zambia. The final dendroid-haired extreme, known from Iringa and Ufipa districts in Tanzania, is smaller than the type form with very densely pubescent ovate leaves. Intermediates are larger with a more lax pubescence, or have both ovate and narrowly ovate-lanceolate leaves. A larger ovate-leaved intermediate is known from N Mozambique and Kasama and Isoka districts in Zambia. An intermediate with two leaf types is known from Iringa and Songea districts in Tanzania and Niassa Province in Mozambique, Zambia (Mbala Dist.) and Malawi (Nkhata Bay Dist.). Zimbabwe (Mazowe, Charter and Harare districts), Tanzania (Mbeya, Iringa, Songea and Ludewa districts) and Zambia (Lusaka). The first of the four extremes has narrow lanceolate leaves as small as 6 mm wide densely covered with stellate and dendroid hairs. Intermediates between this and the type form have broader leaves with a more lax pubescence. It is known from Tanzania (Ufipa Dist.) with intermediates from Zambia (Mbala and Mpika districts).