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The grass genera of the world

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

Sclerochloa P. Beauv.

From the Greek skleros ??? (hard) and chloë (grass), alluding to leathery glumes and lemmas.

Type species: Type: S. dura (L.) P.Beauv.

Including Amblychloa Link, Crassipes Swallen

Habit, vegetative morphology. Annual; caespitose. Culms 4–30 cm high; herbaceous. Culm nodes glabrous. Culm internodes solid. Leaves non-auriculate. Sheath margins joined to free. Leaf blades linear; apically cucullate; narrow; flat, or rolled; without cross venation; persistent; once-folded in bud. Ligule an unfringed membrane; not truncate; 0.5–1.5 mm long.

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

Inflorescence. Inflorescence one-sided, a single raceme, or paniculate (with short, stout branches); contracted (narrow, rigid). Primary inflorescence branches borne biseriately on one side of the main axis. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets secund; pedicellate (the pedicels stout, to 1 mm long).

Female-fertile spikelets. Spikelets 6–15 mm long; compressed laterally; falling with the glumes (and with the pedicel); tardily disarticulating between the florets, or not disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus absent.

Glumes two; very unequal; shorter than the spikelets; shorter than the adjacent lemmas; dorsiventral to the rachis; hairless; glabrous; not pointed (obtuse to emarginate); awnless; non-carinate; similar (herbaceous with membranous margins, oblong-ovate, somewhat asymmetric). Lower glume (1–)3–5 nerved. Upper glume 5–9 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.

Female-fertile florets 3–8. Lemmas decidedly firmer than the glumes (leathery, the margins membranous); not becoming indurated; entire, or incised; blunt; not deeply cleft (rounded to emarginate); awnless; hairless; glabrous; non-carinate; 5–7 nerved. Palea present; relatively long; not indurated (hyaline); 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed. Anthers 0.6–1.5 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small (2.5–3.5 mm long); trigonous. Hilum short (round). Embryo small; not waisted. Endosperm hard; with lipid, or without lipid. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular to fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common; 21–27 microns long (S. dura), or 33–39 microns long (S. rigida). Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; not paired (solitary); not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth (predomonating), or rounded (some, oval); not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade ‘nodular’ in section; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Bulliforms not present in discrete, regular adaxial groups (apart from the ‘midrib hinges’). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Chromosomes ‘large’.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Coleanthinae. 2 species.

Distribution, phytogeography, ecology. Southern Europe to western Asia.

Commonly adventive. Mesophytic to xerophytic; species of open habitats; halophytic to glycophytic (in dry weedy places and saline soils).

Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: ‘Uromycesdactylidis.

References, etc. Leaf anatomical: studied by us - S. dura (L.) Beauv.

Illustrations. • S. dura: P. Beauv. (1812). • Inflorescence detail of S. dura. • Spikelet of S.dura. • S. dura, abaxial epidermis of the leaf blade: this project

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.’.