The grass genera of the world
Type species: Type: P. incurva (L.) C.E.Hubb.
Including Lepidurus Janchen
Habit, vegetative morphology. Slender annual (erect or more or less prostrate); caespitose. Culms 2–50 cm high; herbaceous; branched above, or unbranched above; 3–9 noded. Culm nodes exposed, or hidden by leaf sheaths; glabrous. Culm internodes hollow. Young shoots intravaginal. Leaves not basally aggregated; auriculate, or non-auriculate. Sheaths not keeled. Leaf blades linear; apically cucullate; narrow; 0.4–3 mm wide; setaceous, or not setaceous; flat, or rolled (convolute); without cross venation; persistent; once-folded in bud. Ligule an unfringed membrane; truncate; 0.3–0.9 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality, or of sexually distinct forms on the same plant (sometimes with rudiments at the base of the inflorescence); hermaphrodite, or hermaphrodite and sterile.
Inflorescence. Inflorescence a single spike (cylindrical, rigid, often curved). Rachides hollowed. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes disarticulating; disarticulating at the joints. Spikelets solitary; not secund; distichous; sessile.
Female-fertile spikelets. Spikelets 4–8.5 mm long; more or less abaxial (closing off the hollowed internode); compressed laterally; falling with the glumes (shed with rachis joints). Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets, or naked. Hairy callus absent. Callus absent.
Glumes two; more or less equal; long relative to the adjacent lemmas; lateral to the rachis to displaced (side by side); pointed; awnless; sometimes asymmetric and winged; similar (leathery). Lower glume 3–5 nerved (the nerves raised). Upper glume 3–5 nerved (the nerves raised). Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets if present, distal to the female-fertile florets. The distal incomplete florets 1; merely underdeveloped (a rudiment).
Female-fertile florets 1. Lemmas less firm than the glumes (membranous, side-on to the rachis); not becoming indurated; awnless; hairless; glabrous; non-carinate; 1 nerved, or 3 nerved (the laterals very short). Palea present; relatively long; tightly clasped by the lemma; entire to apically notched; awnless, without apical setae; thinner than the lemma (hyaline); 2-nerved; weakly 2-keeled. Palea keels wingless. Lodicules present; 2; free; membranous; glabrous; not toothed. Stamens 3. Anthers 0.5–4 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (3–3.6 mm long); narrowly ovoid or ellipsoid; ventrally longitudinally grooved, or not grooved; compressed dorsiventrally to not noticeably compressed. Hilum short. Embryo small. Endosperm liquid in the mature fruit, or hard; with lipid; containing compound starch grains. Embryo with an epiblast.
Seedling with a loose coleoptile. First seedling leaf with a well-developed lamina. The lamina narrow; 3 veined.
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; having markedly sinuous walls, or having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare, or common; (39–)42–45(–48) microns long. Subsidiaries low dome-shaped, or parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs (mainly), or not paired (a few solitaries); silicified (when paired). Intercostal silica bodies rounded, or crescentic. Costal short-cells predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies rounded (mostly), or tall-and-narrow to crescentic; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous (rarely), or not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups, or not present in discrete, regular adaxial groups (P. strigosa with small bulliforms of variable size, irregularly grouped in the furrows, cf. Ammophila); sometimes in simple fans (e.g. P. incurva). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7, 9, and 19. 2n = 14, 28, 32, 36, 38, and 42. 2, 4, and 6 ploid. Chromosomes large.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Parapholiinae. 6 species.
Distribution, phytogeography, ecology. Western Europe, Mediterranean to India.
Commonly adventive. Species of open habitats; halophytic, or glycophytic. Sandy maritime soils and saltmarshes.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • General aspect (P. incurva): John Curtis, 1824. • P. incurva: Gardner, 1952). • General morphology (P. incurva): Gibbs Russell et al., 1990. • P. strigosa (as Lepturus filiformis), general aspect: Eng. Bot. (1872). • P. incurva as Lepturus, with Psilurus narduroides as Lepturus): Thomé (1885), Flora von Deutschland, Osterreich und der Schweiz
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: 13th November 2017. delta-intkey.com/grass’.