Arthraxon P.Beauv.

First published in Ess. Agrostogr.: 111 (1812)
This genus is accepted
The native range of this genus is Tropical & Subtropical Old World to Central Asia.

Descriptions

Gramineae, T. A. Cope. Flora Zambesiaca 10:4. 2002

Morphology General Habit
Slender annuals; culms geniculate, often trailing and rooting at the decumbent nodes; internodes pilose.
Morphology Leaves Leaf sheaths
Leaf sheaths slightly inflated; ligule membranous; leaf laminas slightly cordate and semi-amplexicaul at the base, pilose with bulbous-based hairs at least below, usually becoming ciliate.
Morphology Reproductive morphology Inflorescences
Racemes in subdigitate groups, slender, ± exserted from the spatheoles; peduncles longer or shorter than the racemes, erect at maturity; internodes and pedicels delicate, filiform, long-ciliate on both margins.
Morphology Reproductive morphology Inflorescences Spikelets
Sessile spikelet laterally compressed, with silvery-white appressed hairs at the base, the callus short, truncate; inferior glume chartaceous to coriaceous, rounded on the back, with or without lateral keels; inferior floret reduced to a hyaline lemma; superior floret fertile; fertile lemma bifid almost to the base and with a glabrous, geniculate sub-basal awn; anthers 2.Pedicelled spikelet absent or much reduced.
[FZ]

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

Morphology General Habit
Annuals or perennials with slender, often trailing, culms
Morphology Leaves
Leaf-blades broad, commonly lanceolate, cordate and amplexicaul at the base; ligule membranous
Morphology Reproductive morphology Inflorescences
Inflorescence composed of slender subdigitate racemes, their internodes filiform to linear
Sessile
Sessile spikelet laterally compressed; callus truncate; lower glume chartaceous to coriaceous, rounded on the back, with or without lateral keels, often scabrid or muricate; lower floret reduced to a hyaline lemma; upper floret with hyaline subentire lemma bearing a glabrous geniculate awn from low down on the back
Morphology Reproductive morphology Fruits
Caryopsis terete
Morphology Reproductive morphology Inflorescences Spikelets
Pedicelled spikelet variable, from as large as the sessile to quite suppressed. Sessile spikelet laterally compressed; callus truncate; lower glume chartaceous to coriaceous, rounded on the back, with or without lateral keels, often scabrid or muricate; lower floret reduced to a hyaline lemma; upper floret with hyaline subentire lemma bearing a glabrous geniculate awn from low down on the back
Pedicelled
Pedicelled spikelet variable, from as large as the sessile to quite suppressed.
[FTEA]

M. Thulin et al. Flora of Somalia Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit
Annual or perennial with slender often trailing stems; leaves broad, usually lanceolate, cordate and amplexicaul at the base; ligule membranous
Morphology Reproductive morphology Inflorescences
Inflorescence composed of slender subdigitate racemes, these terminal and axillary but not spathate, their internodes filiform to linear
Morphology Reproductive morphology Inflorescences Spikelets
Sessile spikelet dorsally or laterally compressed; callus truncate; lower glume membranous to coriaceous, usually rounded on the back, with or without lateral keels, often scabrid or muricate; lower floret reduced to a hyaline lemma; upper floret with hyaline subentire lemma bearing a glabrous geniculate awn from low down on the back; caryopsis terete Pedicelled spikelet variable, from as large as the sessile to quite suppressed.
Distribution
Some 22 species in the Old World tropics, mainly in India.
[FSOM]

nonem

Morphology General Habit
Annual (20), or perennial (3). Rhizomes absent (22), or short (1). Stolons absent (22), or present (1). Culms erect (2/22), or geniculately ascending (4/22), or decumbent (7/22), or rambling (13/22); slender (6/8), or weak (2/8); 5-41.5-200 cm long; firm (22), or wiry (1); rooting from lower nodes (9/9). Lateral branches lacking (1/5), or sparse (2/5), or ample (3/5). Ligule an eciliate membrane (3), or a ciliolate membrane (17), or a ciliate membrane (2), or a fringe of hairs (1). Leaf-blades lanceolate (22), or ovate (15); firm (17), or flaccid (6).
Morphology Reproductive morphology Inflorescences
Inflorescence composed of racemes. Racemes single (4), or paired (10), or digitate (20), or borne along a central axis (1). Rhachis fragile at the nodes; angular (1/1). Rhachis internodes filiform (13), or linear (12). Spikelets solitary (2), or in pairs (21). Fertile spikelets sessile; 1 in the cluster (21/21). Companion sterile spikelets pedicelled (21/21); 1 in the cluster (21/21). Pedicels filiform (12/22), or linear (9/22), or reduced to a stump (1/22).
Morphology Reproductive morphology Inflorescences Spikelets
Companion sterile spikelets absent (2), or represented by barren pedicels (11), or represented by single glumes (2), or well-developed (9). Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets linear (2), or lanceolate (20), or elliptic (2), or ovate (1); laterally compressed (20), or subterete (1), or dorsally compressed (2); 0.8-5.191-10 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus brief (22), or square (1); glabrous (7/16), or pubescent (9/16), or pilose (1/16), or bearded (1/16); base truncate (19/21), or obtuse (2/21); attached transversely.
Sterile
Companion sterile spikelets absent (2), or represented by barren pedicels (11), or represented by single glumes (2), or well-developed (9).
Fertile
Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets linear (2), or lanceolate (20), or elliptic (2), or ovate (1); laterally compressed (20), or subterete (1), or dorsally compressed (2); 0.8-5.191-10 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus brief (22), or square (1); glabrous (7/16), or pubescent (9/16), or pilose (1/16), or bearded (1/16); base truncate (19/21), or obtuse (2/21); attached transversely.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate (22), or elliptic (1), or ovate (1); chartaceous (20), or coriaceous (3); without keels (17), or 2-keeled (6); 2-4 -veined (1/17), or 5 -veined (4/17), or 6 -veined (3/17), or 7 -veined (11/17), or 8 -veined (3/17), or 9 -veined (6/17), or 10-11 -veined (1/17). Lower glume lateral veins obscure (2), or distinct (21); intercarinal veins distinct (1/1). Lower glume surface convex (22), or flat (1); smooth (5), or asperulous (2), or scabrous (10), or spinose (7), or muricate (2); glabrous (21), or pubescent (1), or pilose (1), or villous (1). Lower glume apex entire (22), or dentate (1); 2 -fid (1/1); obtuse (1/10), or acute (7/10), or acuminate (1/10), or attenuate (1/10). Upper glume lanceolate; membranous (3), or chartaceous (20); with undifferentiated margins (22), or hyaline margins (1); 1-keeled; 3 -veined (15/16), or 4-5 -veined (2/16), or 7 -veined (1/16). Upper glume primary vein eciliate (21), or ciliolate (1), or ciliate (1). Upper glume surface smooth (20), or scabrous (3); glabrous (21), or pilose (2). Upper glume apex obtuse (1/22), or acute (21/22), or setaceously attenuate (1/22); muticous (22), or awned (1); 1 -awned (1/1).
Morphology Reproductive morphology Flowers Florets
Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate (6), or oblong (17); hyaline; 0 -veined (10/18), or 2 -veined (8/18), or 3 -veined (1/18); obtuse (10/10). Fertile lemma linear (1), or lanceolate (17), or oblong (4), or ovate (1); hyaline; without keel; 0 -veined (1/22), or 1 -veined (20/22), or 2 -veined (1/22). Lemma apex entire (16), or dentate (3), or lobed (5); 2 -fid (8/8); acute (18/18); muticous (2), or awned (22); 1 -awned (22/22). Principal lemma awn dorsal (22/22); geniculate (22/22). Palea present (2), or absent or minute (21). Palea surface glabrous (1/2), or pubescent (1/2).
Morphology Reproductive morphology Flowers
Anthers 2-3 (12).
Morphology Reproductive morphology Fruits
Caryopsis with adherent pericarp (18/18); linear (2/5), or fusiform (1/5), or ellipsoid (1/5), or oblong (2/5); isodiametric (1/1).
Distribution
Africa (6), or Temperate Asia (14), or Tropical Asia (19), or Australasia (2), or Pacific (1), or North America (1), or South America (1).
[GB]

Sources

  • Flora Zambesiaca

    • Flora Zambesiaca
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Flora of Somalia

    • Flora of Somalia
    • 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

    • '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.
  • 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