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The grass genera of the world

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

Hakonechloa Makino

Habit, vegetative morphology. Perennial; rhizomatous. Culms 30–60 cm high; herbaceous; to 2 cm in diameter; unbranched above. Culm nodes glabrous. Rhizomes leptomorph. Plants unarmed. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; 2–8 mm wide; not pseudopetiolate; without cross venation. Ligule a fringed membrane. Contra-ligule present (the adaxial ligule continued as a fringe of hairs around the back).

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

Inflorescence. Inflorescence paniculate (small); open; with capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund.

Female-fertile spikelets. Spikelets 9–11 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy (with long white hairs, above the disarticulation zones); the rachilla extension with incomplete florets. Hairy callus present (slender).

Glumes two; very unequal; shorter than the adjacent lemmas; hairless; glabrous; pointed; awnless; non-carinate; very dissimilar. Lower glume 3 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 3–6. Lemmas acuminate; similar in texture to the glumes (herbaceous/membranous); not becoming indurated; entire (or sometimes with a slight notch); pointed; awned. Awns 1; median; apical; non-geniculate; hairless (scabrid); much shorter than the body of the lemma to about as long as the body of the lemma. Lemmas hairy (along the margins); non-carinate (rounded); having the margins lying flat on the palea; without a germination flap; 3 nerved. Palea present; relatively long; slightly apically notched; awnless, without apical setae; not indurated (thinly membranous); 2-nerved; 2-keeled. Lodicules present; free; fleshy; glabrous; heavily vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; brown (apparently).

Fruit, embryo and seedling. Fruit free from both lemma and palea. Pericarp free. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type (both cells long, the apical very flimsy); (44–)48–60(–62) microns long. Microhair apical cells 29–39 microns long. Microhair apical cell/total length ratio 0.62. Stomata absent or very rare. Intercostal short-cells common; not paired (solitary); not silicified. Costal prickles present. Crown cells absent. Costal short-cells conspicuously in long rows (some veins), or neither distinctly grouped into long rows nor predominantly paired (the long-cells often short). Costal silica bodies ‘panicoid-type’; cross shaped, butterfly shaped, and dumb-bell shaped, or nodular.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; with fusoids (seemingly), or without fusoids (need to see fresh material). Leaf blade adaxially flat (low abaxial ribs). Midrib conspicuous (a larger bundle, with a slight double keel); 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 (with all the bundles); forming ‘figures’ (in the midrib). Sclerenchyma all associated with vascular bundles.

Phytochemistry. Leaves without flavonoid sulphates (H. macra).

Cytology. 2n = 50.

Classification. Watson & Dallwitz (1994): Arundinoideae; Arundineae. Soreng et al. (2015): Arundinoideae; Molinieae. 1 species.

Distribution, phytogeography, ecology. Japan.

Mesophytic; glycophytic. On wet cliffs.

References, etc. Leaf anatomical: Metcalfe 1960; this project.

Special comments. Fruit data wanting.


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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: 13th November 2017. delta-intkey.com/grass’.

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