Poaceae
Eragrostis

Eragrostis riobrancensis Judz. & P.M.Peterson

First published in Brittonia 42: 47 (1990)
This species is accepted
The native range of this species is Guyana to N. Brazil. It is a perennial and grows primarily in the wet tropical biome.

Descriptions

Morphology General Habit
Perennial. Culms geniculately ascending; 30-70 cm long. Lateral branches lacking. Ligule a ciliate membrane; 0.2-0.3 mm long. Leaf-blades persistent, or deciduous at the ligule; flat, or involute; 4-8 cm long; 1-2.5 mm wide. Leaf-blade surface glabrous. Leaf-blade apex acuminate.
Morphology Reproductive morphology Inflorescences
Inflorescence a panicle; exserted, or embraced at base by subtending leaf. Panicle open; ovate; 7-11 cm long; 3-6 cm wide. Primary panicle branches 3-5 in number; ascending; 1-3.5 cm long. Panicle branches scaberulous; glabrous in axils. Spikelets solitary. Fertile spikelets pedicelled.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets comprising 7-17 fertile florets; with diminished florets at the apex. Spikelets linear, or oblong; laterally compressed; 5.5-14 mm long; 1.5-2.5 mm wide; breaking up at maturity; rhachilla persistent; retaining paleas; tough throughout, or fragile above.
Fertile
Spikelets comprising 7-17 fertile florets; with diminished florets at the apex. Spikelets linear, or oblong; laterally compressed; 5.5-14 mm long; 1.5-2.5 mm wide; breaking up at maturity; rhachilla persistent; retaining paleas; tough throughout, or fragile above.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes deciduous; similar; shorter than spikelet. Lower glume ovate; 0.5-1.5 mm long; 0.3-0.6 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume ovate; 1.8-2.5 mm long; 0.7-0.8 length of adjacent fertile lemma; membranous; 1-keeled; 1 -veined. Upper glume lateral veins absent. Upper glume apex acute.
Morphology Reproductive morphology Flowers Florets
Fertile lemma elliptic; 2.2-3 mm long; membranous; keeled; 3 -veined. Lemma apex acute. Palea bowed outwards; 1.5-2 mm long. Palea keels winged; narrowly winged; scaberulous. Apical sterile florets resembling fertile though underdeveloped.
Morphology Reproductive morphology Flowers
Lodicules 2; cuneate; fleshy. Anthers 2; 0.2-0.35 mm long; purple.
Morphology Reproductive morphology Fruits
Caryopsis with adherent pericarp; ellipsoid; 0.7-0.8 mm long.
Morphology Reproductive morphology Flowers Cleistogene
Cleistogenes present; in upper sheaths.
Distribution
South America: northern South America and Brazil.
Reference
Eragrostideae. Judz 1995.
[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: low confidence
[AERP]

Sources

  • Angiosperm Extinction Risk Predictions v1

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

  • 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

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. 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 2025. 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