Poaceae
Digitaria

Digitaria rukwae Clayton

First published in Kew Bull. 29: 520 (1974)
This species is accepted
The native range of this species is Tanzania to KwaZulu-Natal. It is a perennial and grows primarily in the seasonally dry tropical biome.

Descriptions

Gramineae, W. D. Clayton. Flora Zambesiaca 10:3. 1989

Morphology General Habit
A caespitose perennial, with a well grown rhizome, covered at the base by cataphylls.
Morphology Culms
Culms 40–110 cm., erect, glabrous, nodes dark and glabrous.
Morphology Leaves Leaf sheaths
Leaf sheaths glabrous, smooth to scaberulous.
Morphology Leaves Ligules
Ligule up to 3 mm. long, triangular to truncate.
Morphology Leaves Leaf lamina
Leaf laminae 7–20 × 0.3–0.7 cm., linear, flat, glabrous and smooth to scaberulous on both surfaces, scabrous along the margins.
Morphology Reproductive morphology Inflorescences
Inflorescence composed of (9)11–21 racemes, 2–11 cm. long, sometimes with a inferior whorl of 3–4 racemes, or all racemes solitary along a well grown common axis, often as long as the largest raceme.
Morphology Leaves Rachis
Rhachis triquetrous, scarcely winged, up to 0.3 mm. broad, smooth to scabrous with a scaberulous margin.
Morphology Reproductive morphology Flowers Pedicel
Pedicels 2-nate, 0.5–2.5 mm. long, subtriangular to compressed, scaberulous, broadened at the apex.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets 2.3–2.9 mm. long, oblong.
Morphology Reproductive morphology Inflorescences Bracts Glume
Inferior glume up to 0.5 mm. long, ovate to triangular, often with a hyaline margin. Superior glume c.3/4 of to as long as the spikelet, 3-nerved, appressed hairy, hairs very fine, white, smooth, acute.
Inferior
Inferior glume up to 0.5 mm. long, ovate to triangular, often with a hyaline margin. Inferior lemma as long as the spikelet, oblong, 7-nerved, central zone somewhat broadened, nerves smooth, appressed hairy.
Morphology Reproductive morphology Inflorescences Bracts Lemma
Superior lemma somewhat smaller than the spikelet, oblong, slightly acuminate, reddish to dark brown. Inferior lemma as long as the spikelet, oblong, 7-nerved, central zone somewhat broadened, nerves smooth, appressed hairy.
Superior
Superior lemma somewhat smaller than the spikelet, oblong, slightly acuminate, reddish to dark brown. Superior glume c.3/4 of to as long as the spikelet, 3-nerved, appressed hairy, hairs very fine, white, smooth, acute.
[FZ]

Morphology General Habit
Perennial. Rhizomes elongated; scaly. Butt sheaths glabrous, or pubescent. Culms 25-120 cm long; spongy. Culm-nodes glabrous. Ligule an eciliate membrane. Leaf-blades 5-30 cm long; 2-7 mm wide.
Morphology Reproductive morphology Inflorescences
Inflorescence composed of racemes. Racemes 6-25; borne along a central axis; simply spaced, or in several whorls; unilateral; 4-10 cm long. Central inflorescence axis 4-20 cm long. Rhachis wingless; angular. Spikelets in pairs. Fertile spikelets pedicelled; 2 in the cluster. Pedicels unequal.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 2-2.6 mm long; with hairs extending 0 mm beyond apex; falling entire.
Fertile
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 2-2.6 mm long; with hairs extending 0 mm beyond apex; falling entire.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes two; dissimilar; reaching apex of florets, or shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 0.1-0.5 mm long; 0.05-0.2 length of spikelet; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume apex obtuse. Upper glume elliptic; 0.75-1 length of spikelet; membranous; without keels; 3(-5) -veined. Upper glume surface pubescent, or pilose. Upper glume apex acute.
Morphology Reproductive morphology Flowers Florets
Basal sterile florets barren; without significant palea. Lemma of lower sterile floret elliptic; 1 length of spikelet; membranous; 7 -veined; pubescent, or pilose; acute. Fertile lemma elliptic; 2-2.5 mm long; cartilaginous; much thinner on margins; light brown; without keel. Lemma margins flat; covering most of palea. Lemma apex acute. Palea cartilaginous.
Distribution
Africa: east tropical, southern tropical, and south.
Reference
Paniceae. FTEA.
[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]

Gramineae, W. D. Clayton, S. M. Phillips & S. A. Renvoize. Flora of Tropical East Africa. 1974

Morphology General Habit
Perennial with scaly rhizomes, the basal sheaths glabrous or silky pubescent; culms 25–120 cm. high, soft; nodes glabrous.
Morphology Leaves
Leaf-blades 5–30 cm. long, 2–7 mm. wide.
Morphology Reproductive morphology Inflorescences
Inflorescence narrowly ovate, of 6–25 racemes borne irregularly or in untidy whorls upon an axis 4–20 cm. long, this often, but not always, longer than the racemes, with or without occasional long white hairs; racemes 4–10 cm. long, the spikelets paired (or sometimes the pedicel forked) on a triquetrous rhachis.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets elliptic, 2–2.6 mm. long; lower glume triangular to ovate, 0.1–0.5 mm. long; upper glume 3/4 to almost as long as the spikelet, 3(–5)-nerved, pubescent to pilose; lower lemma as long as the spikelet, 7-nerved, pubescent to pilose with fine soft smooth hairs, the hairs not extending beyond the spikelet; fruit ellipsoid, brown.
Habitat
Food plains and alluvial soils; 0–2000 m.
Distribution
T1 T3 T4 T7
[FTEA]

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

  • 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

    • 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