Poaceae
Cenchrus

Cenchrus gracillimus Nash

First published in Bull. Torrey Bot. Club 22: 300 (1895)
This species is accepted
The native range of this species is SE. U.S.A., Caribbean. It is an annual or perennial and grows primarily in the seasonally dry tropical biome.

Descriptions

Morphology General Habit
Annual; caespitose. Culms 15-60 cm long. Leaf-sheaths keeled; glabrous on surface, or pilose. Ligule a fringe of hairs; 0.2-0.6 mm long. Leaf-blades 4.5-17 cm long; 1.1-3.3 mm wide. Leaf-blade surface smooth, or scabrous.
Morphology Reproductive morphology Inflorescences
Inflorescence a panicle. Panicle spiciform; linear; loose (internodes 4-10mm); 2-6.8 cm long; 0.8-1.9 cm wide. Primary panicle branches accrescent to a central axis; with sessile scars on axis. Panicle axis angular; scabrous; bearing deciduous spikelet clusters. Spikelets subtended by an involucre. Fertile spikelets sessile; 1-3 in the cluster. Involucre composed of bristles; connate into a cup below; ovate; 5.2-12.9 mm long; base obconical; base glabrous. Involucral bristles deciduous with the fertile spikelets; emerging irregularly from body of a burr; 3.2-6 mm long; flattened; rigid; retrorsely scaberulous; glabrous.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; acuminate; 4-6.5 mm long; falling entire; deciduous with accessory branch structures.
Fertile
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; acuminate; 4-6.5 mm long; falling entire; deciduous with accessory branch structures.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 1.4-3.1 mm long; 0.3-0.5 length of spikelet; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume ovate; 3.2-5.4 mm long; 0.75 length of spikelet; membranous; without keels; 3-5 -veined. Upper glume apex acute.
Morphology Reproductive morphology Flowers Florets
Basal sterile florets barren; with palea. Lemma of lower sterile floret ovate; 4.1-6 mm long; 1 length of spikelet; membranous; 3-5 -veined; acute. Fertile lemma ovate; 3.9-6.5 mm long; coriaceous; much thinner on margins; without keel; 3 -veined. Lemma margins flat. Lemma apex obtuse. Palea coriaceous.
Morphology Reproductive morphology Flowers
Anthers 0.9-1.9 mm long.
Morphology Reproductive morphology Fruits
Caryopsis with adherent pericarp.
Distribution
North America: southeast USA. South America: Caribbean.
Reference
Paniceae. De Lisle.
[GB]

Sources

  • 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 2023. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2022 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 2023. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2022 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0