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The grass genera of the world

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

Gouldochloa Valdés, Morden & Hatch

Named for Frank Gould (North American agrostologist), with Greek chloa (a grass).

~ Chasmanthium

Habit, vegetative morphology. Perennial; caespitose. The flowering culms leafy (but differing from the non-flowering culms in having elongated internodes). Culms 30–60 cm high (usually erect, sometimes decumbent to ascending); herbaceous; to 0.26 cm in diameter; unbranched above (seemingly). Leaves not basally aggregated; auriculate; with auricular setae (or at least, the auricles pilose). Leaf blades linear; narrow; 2–3.1 mm wide (and 3–7 cm long); flat, or rolled (inrolled or involute); not pseudopetiolate; without cross venation; persistent (the senescent tips becoming spirally coiled). Ligule present; a fringed membrane.

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

Inflorescence. Inflorescence paniculate; contracted (spikelike, with short, rigid, closely appressed primary branches); spicate; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs (in that the lowermost spikelets of primary branches are often subtended by a 0.5–3.5 mm scale). Spikelet-bearing axes persistent. Spikelets solitary; not secund.

Female-fertile spikelets. Spikelets 8–16 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairless.

Glumes two; more or less equal (subequal, the G1 being slightly longer); shorter than the adjacent lemmas; hairless; awnless; seemingly non-carinate (but the nerves ‘protruding abaxially’); similar (pale green, chartaceous, with hyaline margins). Lower glume 7 nerved, or 9 nerved. Upper glume 7 nerved, or 9 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets, or both distal and proximal to the female-fertile florets (the lowemost floret staminate or perfect, the upper florets male or neuter). The distal incomplete florets usually several; merely underdeveloped. The proximal incomplete florets when present, 1; when present, paleate; when present, male. The proximal lemmas awnless; 7 nerved, or 9 nerved; exceeded by the female-fertile lemmas; similar in texture to the female-fertile lemmas (rigid, chartaceous); not becoming indurated.

Female-fertile florets 1, or 2 (the second, and sometimes the third). Lemmas similar in texture to the glumes (rigid, chartaceous, with hyaline margins); not becoming indurated; entire; awnless; glabrous except for a tuft near the callus; non-carinate (seemingly, though the nerves prominent); without a germination flap (or at least, no flap mentioned); 7 nerved, or 9 nerved. Palea present; relatively long to conspicuous but relatively short (subequal with to 3mm shorter than the lemma); apically notched (the teeth 0.3–0.4 mm long); awnless, without apical setae; texture unstated; not indurated; 2-nerved; sharply 2-keeled. Lodicules present; 2; free; glabrous; regularly 3-lobed; not or scarcely vascularized (obscurely 3 nerved). Stamens 1 (anterior to the pistil). Anthers 1.5–2.1 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Stigmas 2; red pigmented.

Fruit, embryo and seedling. Fruit small (about 3 mm long); compressed laterally (ovate to triangular in section). Hilum short (probably, but unstated). Pericarp fused (yellow brown above, golden brown below). Embryo small (1/5 of the caryopsis length); with 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 markedly different in shape costally and intercostally (the costals much narrower). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common. Subsidiaries triangular. Intercostal short-cells absent or very rare (seemingly). Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; cross shaped and dumb-bell shaped.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; seemingly without arm cells; without fusoids. Leaf blade with distinct, prominent adaxial ribs to ‘nodular’ in section. 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.

Cytology. Chromosome base number, x = 12. 2n = 24. 2 ploid.

Classification. Watson & Dallwitz (1994): Centothecoideae; Centotheceae. Soreng et al. (2015): Panicoideae; Chasmanthieae. 1 species.

Distribution, phytogeography, ecology. Mexico.

Xerophytic; species of open habitats. In desert scrub.

References, etc. Morphological/taxonomic: Valdés, Morden and Hatch 1986.


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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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