Poaceae
Coix

Coix aquatica Roxb.

First published in Fl. Ind., ed. 1832. 3: 571 (1832)
This species is accepted
The native range of this species is India to China (Yunnan, Guangdong, Guangxi) and Peninsula Malaysia. It is a perennial and grows primarily in the wet tropical biome.

Descriptions

Morphology General Habit
Annual. Culms rambling; 60-150 cm long; spongy. Culm-nodes glabrous. Leaves cauline. Ligule an eciliate membrane; 1 mm long. Leaf-blade base cordate. Leaf-blades linear, or lanceolate; 8-45 cm long; 8-25 mm wide; glandular. Leaf-blade surface pilose; hairy adaxially; with tubercle-based hairs. Leaf-blade margins ciliate. Leaf-blade apex acuminate.
Morphology Reproductive morphology Inflorescences
Monoecious; with a male and a female inflorescence subtended by the same spatheole. Synflorescence compound; paniculate; prophyllate below lateral spikelets (female inflorescence). Inflorescence composed of racemes; axillary; deciduous as a whole; subtended by a spatheole; exserted (male), or enclosed (female). Spatheole ovate (and beaked); 10-11 cm long; indurate. Peduncle straight; 3-7 cm long; glabrous; widened at apex; disarticulating; disarticulating below uppermost sheaths. Racemes 1; single; bearing a triad of spikelets. Rhachis obsolete. Spikelets in threes. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 2 in the cluster. Male spikelets sessile, or pedicelled; 2-3 in a cluster. Pedicels linear; 1 length of fertile spikelet. Male inflorescence unlike female; a single raceme. Male spikelets distinct from female; 2 flowered; elliptic; 11-12 mm long (4-6mm wide). Male spikelet glumes 2; winged; muticous. Male spikelet lemma muticous.
Sterile
Companion sterile spikelets represented by barren pedicels.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 8-9 mm long; falling entire; deciduous with accessory branch structures. Companion sterile spikelets represented by barren pedicels.
Fertile
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 8-9 mm long; falling entire; deciduous with accessory branch structures.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes dissimilar; reaching apex of florets; similar to fertile lemma in texture. Lower glume lanceolate, or oblong; 8-9 mm long; 1 length of spikelet; chartaceous; without keels. Lower glume surface flat. Lower glume apex cuspidate. Upper glume oblong; hyaline; 1-keeled. Upper glume primary vein grooved on either side. Upper glume apex cuspidate.
Morphology Reproductive morphology Flowers Florets
Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate, or oblong; 1 length of spikelet; membranous; 5 -veined; acuminate. Fertile florets female. Fertile lemma lanceolate, or oblong; 7.5-8.5 mm long; membranous; keeled; 5 -veined. Lemma lateral veins obscure. Lemma surface with 2 longitudinal grooves. Lemma apex acuminate. Palea hyaline; 2 -veined; without keels.
Morphology Reproductive morphology Flowers
Lodicules absent (female), or 2 (male); cuneate; fleshy. Anthers 3; 6-6.5 mm long. Stigmas 2; papillose. Styles connate below.
Morphology Reproductive morphology Fruits
Caryopsis with adherent pericarp. Disseminule comprising a inflorescence.
sex Male
Male inflorescence unlike female; a single raceme. Male spikelets distinct from female; 2 flowered; elliptic; 11-12 mm long (4-6mm wide). Male spikelet glumes 2; winged; muticous. Male spikelet lemma muticous.
Distribution
Asia-temperate: China. Asia-tropical: India and Indo-China. Australasia: Australia.
Reference
Andropogoneae. Patunkar 1993.
[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

  • 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