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The grass genera of the world

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

Scutachne A. Hitchc. & Chase

Habit, vegetative morphology. Perennial; caespitose. Culms 40–70 cm high; herbaceous. Culm nodes glabrous. Leaves mostly basal; non-auriculate. Leaf blades narrow; 4–6(–10) mm wide; without cross venation; persistent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality (the short-pedicelled members poorly-developed or missing); hermaphrodite and sterile.

Inflorescence. Inflorescence a single spike (contracted about the primary branches), or paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate; consistently in ‘long-and-short’ combinations, or not in distinct ‘long-and-short’ combinations; sometimes unequally pedicellate in each combination. The ‘shorter’ spikelets sterile. The ‘longer’ spikelets hermaphrodite.

Female-fertile spikelets. Spikelets 5 mm long; compressed dorsiventrally; falling with the glumes; with a distinctly elongated rachilla internode between the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; relatively large; very unequal; (the upper) about equalling the spikelets (the lower half as long); (the upper) long relative to the adjacent lemmas; (the upper) hairy; pointed; awnless; non-carinate; very dissimilar (the lower small, hyaline and appressed to the rachilla, the upper large and firm). Lower glume 7–9 nerved. Upper glume 7 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 not becoming conspicuously hardened and enlarged laterally. The proximal incomplete florets male. The proximal lemmas awnless; 5 nerved; more or less equalling the female-fertile lemmas; less firm than the female-fertile lemmas (leathery, like the upper glume).

Female-fertile florets 1. Lemmas acuminate to a puberulous point; similar in texture to the glumes to decidedly firmer than the glumes; pointed; awnless; hairless; non-carinate; having the margins lying flat on the palea; with a clear germination flap; 5 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; red pigmented.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; panicoid-type; 60–66 microns long; 6–8.4 microns wide at the septum. Microhair total length/width at septum 7.1–11. Microhair apical cells 28.5–36 microns long. Microhair apical cell/total length ratio 0.45–0.55. Stomata common; 27–33 microns long. Subsidiaries dome-shaped (mostly), or triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs. Costal short-cells conspicuously in long rows. Costal silica bodies horizontally-elongated smooth and ‘panicoid-type’; mostly cross shaped and nodular; not sharp-pointed.

Transverse section of leaf blade, physiology. C4; XyMS+. PCR sheath outlines uneven. Mesophyll with radiate chlorenchyma. Leaf blade ‘nodular’ in section; with the ribs more or less constant in size. 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 (with the bigger bundles); forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Melidininae. 2 species.

Distribution, phytogeography, ecology. Cuba.

Species of open habitats. Rocky slopes.

References, etc. Leaf anatomical: S. dura studied by us.

Special comments. Fruit data wanting. Illustrations. • S. dura: Hitchcock (1936)

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: 11th December 2017.’.