Poaceae
Hyparrhenia

Hyparrhenia involucrata Stapf

First published in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 9: 376 (1919)
This species is accepted
The native range of this species is W. Tropical Africa to Chad. It is an annual and grows primarily in the seasonally dry tropical biome.

Descriptions

Gramineae, W. D. Clayton. Flora of West Tropical Africa 3:2. 1972

Morphology General Habit
Robust annual 2 m. high
Ecology
In savanna, particularly on dry or shallow soils.
[FWTA]

Morphology General Habit
Annual. Butt sheaths glabrous. Culms erect; robust; 100-200 cm long. Culm-nodes glabrous, or bearded. Leaves cauline. Leaf-sheath oral hairs bearded (grey hairs). Ligule a ciliolate membrane; 1-2 mm long. Leaf-blades 20-40 cm long; 4-8 mm wide; flaccid; light green. Leaf-blade surface glabrous, or pilose; hairy abaxially. Leaf-blade margins scabrous.
Morphology Reproductive morphology Inflorescences
Synflorescence compound; paniculate; 20-60 cm long. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; enclosed. Spatheole lanceolate; 4-7 cm long; scarious; yellow and purple; glabrous. Peduncle 2-3 cm long; glabrous, or pilose above (at base). Racemes 2; paired; deflexed; 1.5-2.3 cm long; bearing few fertile spikelets; bearing 1-2 fertile spikelets on each. Rhachis fragile at the nodes; ciliate on margins. Rhachis internodes linear. Rhachis internode tip oblique; flat. Raceme-bases flattened; subequal; 1.5 mm long; pubescent. Spikelets appressed; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; flattened; ciliate; tip oblique.
Sterile
Basal sterile spikelets well-developed; on lower raceme 4 in number; 4 in upper raceme; forming an involucre about the fertile; lanceolate; 7-15 mm long; equalling fertile. Basal sterile spikelet glumes scabrous on margins, or ciliate on margins; lower glume muticous. Companion sterile spikelets well-developed; containing empty lemmas, or male; lanceolate; dorsally compressed; 7-11 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; acute; awned; one glume awned; with 1-20 mm long awn. Companion sterile spikelet lemmas 2; enclosed by glumes.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 7-8 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus linear; 2-2.5 mm long; pubescent; base pungent; attached obliquely. Basal sterile spikelets well-developed; on lower raceme 4 in number; 4 in upper raceme; forming an involucre about the fertile; lanceolate; 7-15 mm long; equalling fertile. Basal sterile spikelet glumes scabrous on margins, or ciliate on margins; lower glume muticous. Companion sterile spikelets well-developed; containing empty lemmas, or male; lanceolate; dorsally compressed; 7-11 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; acute; awned; one glume awned; with 1-20 mm long awn. Companion sterile spikelet lemmas 2; enclosed by glumes.
Fertile
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 7-8 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus linear; 2-2.5 mm long; pubescent; base pungent; attached obliquely.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of spikelet; coriaceous; without keels; keel-less except near apex. Lower glume surface glabrous to pubescent. Lower glume apex dentate; 2 -fid. Upper glume linear; coriaceous; without keels.
Morphology Reproductive morphology Flowers Florets
Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 1 length of fertile lemma; hyaline; 2 -veined. Fertile lemma linear; membranous; without keel; 1 -veined. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 70-110 mm long overall; with twisted column. Column of lemma awn hirsute; with 0.5-1 mm long hairs. Palea absent or minute.
Morphology Reproductive morphology Flowers
Lodicules 2; cuneate; fleshy. Anthers 3. Stigmas 2.
Morphology Reproductive morphology Fruits
Caryopsis 3.5 mm long.
Distribution
Africa: west tropical, west-central tropical, and northeast tropical.
Reference
Andropogoneae. WDC.
[GB]

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]

Sources

  • Angiosperm Extinction Risk Predictions v1

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

  • Flora of West Tropical Africa

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

  • GrassBase - The Online World Grass Flora

    • Clayton, W.D., Vorontsova, M.S., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora.
    • 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 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