The grass genera of the world
Including Haynaldia Schur, Pseudosecale (Godron) Degen, Secalidium Schur
Habit, vegetative morphology. Annual, or perennial. Culms 20–100 cm high; herbaceous. Leaves auriculate. Sheath margins joined, or free. Leaf blades linear; narrow; 1–5 mm wide; flat; without cross venation. Ligule an unfringed membrane; truncate; 0.3–1 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a single spike (compressed, dense). Rachides hollowed, or flattened, or winged, or neither flattened nor hollowed, not winged. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes disarticulating; disarticulating at the joints. Spikelets solitary; not secund; distichous.
Female-fertile spikelets. Spikelets 7–22 mm long; compressed laterally; falling with the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent. Callus very short.
Glumes two; more or less equal; shorter than the adjacent lemmas; lateral to the rachis, or displaced (and adjacent to one another); with distinct hair tufts; not subulate; awned (both with long, scabrid awns); non-carinate; similar (leathery with membranous margins, abruptly tapering into the awns, strongly 2-keeled, the keels bearing tufts of hair and convergent above). Lower glume two-keeled (with leathery, ciliate keels); 3–4 nerved. Upper glume 3–4 nerved (also bicarinate). Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1(–2) (sterile, long-stipitate).
Female-fertile florets 2(–3). Lemmas similar in texture to the glumes; not becoming indurated; entire, or incised; pointed; when incised, 2 lobed; not deeply cleft (bidentate); awned. Awns 1; median; apical (attenuate from the lemma), or from a sinus; non-geniculate; hairless (scabrid); much longer than the body of the lemma; entered by several veins. Lemmas hairy. The hairs in tufts (on the keel). Lemmas carinate; without a germination flap; 5 nerved. Palea present (narrowly lanceolate); relatively long; membranous; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; ciliate, or glabrous; not toothed; not or scarcely vascularized. Stamens 3. Anthers 5–7 mm long. Ovary apically hairy; with a conspicuous apical appendage (below the styles), or without a conspicuous apical appendage. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea (i.e. threshing free); small to medium sized (3.8–7 mm long); ellipsoid; shallowly longitudinally grooved; slightly to strongly compressed laterally; with hairs confined to a terminal tuft. Hilum long-linear. Embryo small. Endosperm hard; without lipid; containing only simple starch grains. Embryo with an epiblast.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (much narrower costally); fairly thin walled. Mid-intercostal long-cells rectangular to fusiform (some of them extraordinarily long); having straight or only gently undulating walls. Microhairs absent. Stomata common. Subsidiaries non-papillate; parallel-sided. Guard-cells overlapped by the interstomatals (slightly but consistently, but the apparatus not much sunken). Intercostal short-cells fairly common; not paired (solitary, large); not silicified. Small prickles intercostally, larger to very large ones costally. Crown cells absent (many of the small intercostal prickles with reduced or blunt points, but lacking the ring of pits). Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present and well developed; horizontally-elongated crenate/sinuous to horizontally-elongated smooth.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs, or nodular in section; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present (with the primaries); forming figures (a few Is). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 14 and 28. 2 and 4 ploid. Haplomic genome content V. Chromosomes large. Haploid nuclear DNA content 5.4 pg (1 species). Mean diploid 2c DNA value 10.7 pg (1 species).
Classification. Watson & Dallwitz (1994): Pooideae; Triticodae; Triticeae. Soreng et al. (2015): Pooideae; Triticodae; Triticeae; Triticinae. 3–5 species.
Distribution, phytogeography, ecology. Mediterranean.
Xerophytic; species of open habitats. Stony slopes.
Hybrids. Intergeneric hybrids with Aegilops.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia striiformis and Puccinia recondita. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae Tilletia. Ustilaginaceae Ustilago.
References, etc. Morphological/taxonomic: Löve 1984. Leaf anatomical: studied by us - D. villosum (Coss. & Dur.) Dur.
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. delta-intkey.com/grass’.