Orchidaceae
Disa

Disa aperta N.E.Br.

First published in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 7: 286 (1898)
This species is accepted
The native range of this species is SW. & S. Tanzania to Zambia. It is a tuberous geophyte and grows primarily in the seasonally dry tropical biome.

Descriptions

Orchidaceae, V. S. Summerhayes. Flora of Tropical East Africa. 1968

Morphology General Habit
A terrestrial herb 2–4.5 dm. high, glabrous except for the roots.
Vegetative Multiplication Tubers
Tubers ovoid or ellipsoid, 1.5–2.5 cm. long, 1–1.5 cm. in diameter, ± densely tomentose.
Morphology Roots
Roots slender, flexuous, pubescent.
Morphology Stem
Flowering stems erect, rather slender, terete, leafy throughout their length; leaves 4–6, the lowest 1 or 2 sheath-like, obtuse, the remainder erect, ± adpressed to the stem, lanceolate, acute, the largest 4.5–8 cm. long and 5–14 mm. broad, the uppermost often much smaller than the others. Sterile stems only slightly developed at time of flowering, very short, with several overlapping sheaths and a single narrow leaf.
Morphology Reproductive morphology Inflorescences
Inflorescence 4–17 cm. long, 3–4.5 cm. in diameter, rather loosely 6–25-flowered.
Morphology Reproductive morphology Inflorescences Bracts
Bracts thin in texture, lanceolate, acuminate, 8–16 mm. long, shorter than the flowers.
Morphology Reproductive morphology Flowers
Flowers half-spreading, whitish with purple or mauve markings or spots; pedicel with ovary straight, 10–14 mm. long.
Morphology Reproductive morphology Flowers Calyx
Dorsal sepal erect or tilted backwards, convex, broadly elliptical in front, spurred at the back below the middle, 7–11 mm. long, the mouth ± 7 mm. broad when spread out, the spur at right angles, shortly cylindrical from a broader base, total length from base of sepal 6–7 mm.; laterals projecting forwards, oblong-elliptical, rounded, 10–13 mm. long, 4–5 mm. broad, apex shortly mucronate.
Morphology Reproductive morphology Flowers Corolla
Petals inside the dorsal sepal, erect, very obliquely oblanceolate or almost subhastate, acute, 5–7 mm. long, ± 3 mm. broad, attached to the column by a thin keel or ridge.
Morphology Reproductive morphology Flowers Labellum
Lip projecting forwards in a straight line with the ovary, narrowly oblong from a narrower base, obtuse or rounded at the apex, 6–11 mm. long, ± 2 mm. broad.
Morphology Reproductive morphology Flowers Column
Column short, erect; anther reflexed or horizontal, ± 2 mm. long, canals short, turned upwards; stigma almost orbicular, 2 mm. in diameter.
Habitat
In swamps or grassland by streams; 900–2100 m.
Distribution
T7 T8
[FTEA]

Orchidaceae, I. la Croix and P.J. Cribb. Flora Zambesiaca 11:1. 1995

Morphology General Habit
Erect, terrestrial herb, 25–45 cm tall, slender, perennating by tubers.
Morphology Leaves
Leaves usually 3, mostly sheathing, the lowermost foliate, 4–8 cm long, lanceolate to narrowly lanceolate, acute to subacuminate, lax.
Morphology Reproductive morphology Inflorescences
Inflorescence lax, 10–18 cm long, 10–30-flowered.
Morphology Reproductive morphology Inflorescences Bracts
Floral bracts narrowly ovate, acute to acuminate, mauve and possibly dry, about as long as the ovary.
Morphology Reproductive morphology Flowers
Flowers facing somewhat down, sepals mauve-blue to greenish-brown speckled purple, petals white to greenish-brown, lip white with faint spots, spur white.
Morphology Reproductive morphology Flowers Calyx
Dorsal sepal elliptic, acute, forming a galea 6–9(11) mm long, 3.5–5(6) mm wide and 3–4 mm deep. Lateral sepals patent, 7.5–11.5 mm long, oblique, oblong-elliptic, subacute, apiculate.
Morphology Reproductive morphology Flowers Spur
Spur 3–4 mm long, conical to sub-cylindrical, obtuse to rounded, usually horizontal, originating above the base of the galea.
Morphology Reproductive morphology Flowers Corolla
Petals 5.5–6(7) mm long, falcate, acute, triangular in outline, erect inside the galea.
Morphology Reproductive morphology Flowers Labellum
Lip patent, 5.5–8.5 mm long, linear-elliptic, rounded.
Morphology Reproductive morphology Flowers Rostellum
Rostellum 2 mm tall, fused to petals by long keels.
Morphology Reproductive morphology Flowers Androecium Stamens Anthers
Anther 2 mm long.
Morphology Reproductive morphology Flowers Gynoecium Stigma
Stigma subsessile, tripulvinate, almost square.
Morphology Reproductive morphology Flowers Gynoecium Ovary
Ovary 10–15 mm long.
[FZ]

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: threatened. Confidence: low confidence
[AERP]

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0

  • Flora Zambesiaca

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

  • Flora of Tropical East Africa

    • Flora of Tropical East Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Herbarium Catalogue Specimens

    • 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 Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0