Apocynaceae
Xysmalobium

Xysmalobium kaessneri S.Moore

First published in J. Bot. 46: 295 (1908)
This species is accepted
The native range of this species is SW. Tanzania to S. Tropical Africa. It is a perennial or tuberous geophyte and grows primarily in the seasonally dry tropical biome.

Descriptions

Apocynaceae (part 2), David Goyder, Timothy Harris, Siro Masinde, Ulrich Meve, Johan Venter. Flora of Tropical East Africa, 2012

Morphology General Habit
Erect perennial herb arising from a vertical, woody, napiform tuber.
Morphology Stem
Stems usually single, 40–70 cm tall, densely pubescent with short curled hairs
Morphology Leaves
Leaves sessile or with petiole up to 1 cm long; lamina oblanceolate, obovate, oblong or elliptic, 3.5–7(–9) × (0.7–)1–4.5 cm, lower leaves occasionally broadly ovate or suborbicular, apex rounded, retuse or, particularly in upper leaves, acute, base rounded to cuneate, margins smooth or slightly crisped, veins prominent especially on lower surface, reticulate, marginal vein present, with white hairs mainly on the midrib and major veins
Morphology Reproductive morphology Inflorescences
Umbels sessile, extra-axillary, with 5–8 flowers at each of the upper and middle nodes.
Morphology Reproductive morphology Inflorescences Bracts
Bracts linear, 7–9 mm long, acute, moderately to densely pubescent
Morphology Reproductive morphology Flowers Corolla
Corolla campanulate, divided ± to the base, green tinged with purple outside, paler within; lobes ovate, ± 7 × 3.5 mm, acute, outer face pubescent, inner surface minutely pubescent
Morphology Reproductive morphology Flowers Corona
Corona lobes shorter than the staminal column, basal part of each lobe forming a fleshy claw ± 1 × 0.5 mm spreading upwards and outwards from the base of the column, distal part spatulate, very fleshy, spreading ± horizontally from the cavity between adjacent pairs of anther wings, 2–3 × ± 2 × 1 mm, basal margin often produced into a small backward-pointing tongue.
Morphology Reproductive morphology Flowers Gynostegium
Gynostegium ± 3.5 mm high, cylindrical
Morphology Reproductive morphology Flowers Androecium Stamens Anthers
Anther wings ± vertical; appendages ovate, 2.5 × 2 mm, acute, inflexed over the stylar head
Morphology Reproductive morphology Flowers Pollinarium
Pollinaria robust; corpusculum black, ovate, ± 0.5 × 0.4 mm; translator arms dark brown, ± 0.7 × 0.3 mm flattened, the distal end ± as wide as the proximal end of the pollinium.
Morphology Reproductive morphology Flowers Pollinia
Pollinia oblong-obtriangular, 0.7 × 0.4 mm
Morphology Reproductive morphology Flowers Gynoecium Stigma
Apex of stigma head ± 3 mm diameter, flat, ± level with the top of the column and obscured by the anther appendages
Morphology Reproductive morphology Fruits
Follicles erect, narrowly fusiform, up to ± 30 cm long, 2 cm diameter at the widest point, finely rusty-pubescent, only one of the pair developing.
Ecology
Mixed Brachystegia woodland; 1200–1600 m
Distribution
Range: Congo-Kinshasa, Zambia, Malawi and Zimbabwe Flora districts: T7
[FTEA]

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
[AERP]

Goyder, D. J., Gilbert, M. G. & Venter, H. J. T. (2020). Apocynaceae (part 2). In: M. A. García (ed.), Flora Zambesiaca, Vol. 7(3). Royal Botanic Gardens, Kew.

Type
Zambia, Sangolo Spruit, 23.x.1907, Kässner 2104 (BM holotype, K).
Morphology General Habit
Erect perennial herb arising from a vertical, woody, napiform tuber
Morphology Stem
Stems usually single, 40–70 cm tall, densely pubescent with short curled hairs
Morphology Leaves
Leaves sessile or with petiole up to 1 cm long; lamina 3.5–7(9) × (0.7)1–4.5 cm, oblanceolate, obovate, oblong or elliptic, lower leaves occasionally broadly ovate or suborbicular, apex rounded, retuse or, particularly in upper leaves, acute, base rounded to cuneate, margins smooth or slightly crisped, veins prominent especially on lower surface, reticulate, secondary veins at an acute angle to the midrib, marginal nerve present, indumentum of white hairs concentrated mainly on the midrib and major veins
Morphology Reproductive morphology Inflorescences
Umbels sessile, extra-axillary, with 5–8 flowers at each of the upper and middle nodes
Morphology Reproductive morphology Flowers Corolla
Corolla campanulate, divided ± to the base, green tinged with purple outside, paler within; lobes c.7 × 3.5 mm, ovate, acute, outer face pubescent, inner surface minutely pubescent
Morphology Reproductive morphology Flowers Corona
Corona lobes shorter than the staminal column, basal portion of each lobe forming a fleshy claw c.1 × 0.5 mm spreading upwards and outwards from the base of the column, distal portion spathulate, very fleshy, spreading ± horizontally from the cavity between adjacent pairs of anther wings, 2–3 mm long, c.2 mm wide and 1 mm thick, basal margin often produced into a small backward- pointing tongue
Morphology Reproductive morphology Flowers Gynostegium
Gynostegium c.3.5 mm high, cylindrical, the anther wings ± vertical-Pollinaria robust; corpusculum c.0.5 × 0.4 mm, ovate, black; translator arms c.0.7 × 0.3 mm flattened, dark brown, the distal end ± as wide as the proximal end of the pollinium; pollinia 0.7 × 0.4 mm, oblong-obtriangular
Morphology Reproductive morphology Flowers Gynoecium Style
Apex of stylar head c.3 mm diam., flat, ± level with the top of the column
Morphology Reproductive morphology Seeds
Follicles up to c.30 cm long, 2 cm diam. at the widest point, narrowly fusiform, erect, finely rusty- pubescent, only one of the pair developing.
Distribution
Zambia, Zimbabwe, Malawi. Also known from southern Tanzania and D.R. Congo.
Ecology
Brachystegia woodland; 1200– 1600 m.
[FZ]

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