| # The grass genera of the world |

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

### Ancistrachne S. T. Blake

From the Greek (ancistrus) to furnish with barbs, and (achne) husk or glume, referring to the often hooked hairs on the glumes.

Type species: Type: A. uncinulata (R.Br.) S.T.Blake.

Including Simonachne E.J. Thomps.

Habit, vegetative morphology. Perennial (with wiry culms); caespitose, or decumbent (sometimes shrubby, or scrambling). Culms 100–200 cm high; woody and persistent to herbaceous; branched above, or unbranched above. Culm nodes glabrous. Culm leaf sheaths rounded. Culm internodes solid. Young shoots extravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; not pseudopetiolate; without cross venation; disarticulating from the sheaths. Ligule present; a fringe of hairs.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence paniculate, or a single raceme; open (narrow, depauperate, the primary branches sometimes simple). Primary inflorescence branches inserted all around the main axis. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund. Pedicel apices cupuliform.

Female-fertile spikelets. Spikelets 2.2–3.5 mm long; lanceolate; abaxial; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes present; two; very unequal; (the upper) long relative to the adjacent lemmas; dorsiventral to the rachis (the lower abaxial); hairy (hispid with hooked or flexuous hairs, the upper more so); pointed; awnless; non-carinate. Lower glume 0–5 nerved (from vestigial to half the spikelet length). Upper glume 5–11 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets reduced; not becoming conspicuously hardened and enlarged laterally. The proximal incomplete florets sterile. The proximal lemmas hispid, the hairs hooked or flexuous; awnless; 7–9 nerved; more or less equalling the female-fertile lemmas to decidedly exceeding the female-fertile lemmas; less firm than the female-fertile lemmas (leathery); not becoming indurated.

Female-fertile florets 1. Lemmas decidedly firmer than the glumes; smooth; becoming indurated to not becoming indurated (cartilaginous to crustaceous); yellow in fruit, or brown in fruit; entire; pointed, or blunt; awnless to mucronate (the apex incurved); hairless; non-carinate; having the margins lying flat on the palea; with a clear germination flap; 5–7 nerved. Palea present; relatively long; entire; awnless, without apical setae; textured like the lemma; indurated, or not indurated; 2-nerved. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers about 2 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small; compressed dorsiventrally. Hilum short. Pericarp fused. Embryo large. Endosperm containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (but the intercostals shorter); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 48–63 microns long; 6–7.5 microns wide at the septum. Microhair total length/width at septum 6.4–10.5. Microhair apical cells 21–24 microns long. Microhair apical cell/total length ratio 0.35–0.44. Stomata common; 28.5–31.5 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma; without adaxial palisade; Isachne-type. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Neurachninae. 5 species.

Distribution, phytogeography, ecology. Philippines, eastern Australia, New Caledonia.

Shade species. Forests.

References, etc. Morphological/taxonomic: Blake 1941. Leaf anatomical: studied by us - A. uncinulata (R. Br.) Blake.

Special comments. The detailed 2022 taxonomic revision of Ancistrachne sensu lato by E.J. Thompson in Aust. Syst. Bot. 35(1) has yet to be accounted for in this package.

Illustrations. • Ancistrachne uncinulata: Stanley & Ross (1989).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 15th June 2025. delta-intkey.com’.

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