The grass genera of the world
Habit, vegetative morphology. Annual. Culms 10–15 cm high; herbaceous; branched above. Culm nodes exposed; hairy. Plants unarmed. Leaves not basally aggregated; non-auriculate; without auricular setae. Sheaths slightly inflated, not keeled. Leaf blades lanceolate; broad; 3–5 mm wide (1.5–4 cm long); rounded at base; flat; more or less pseudopetiolate; without cross venation. Ligule an unfringed membrane (ciliolate); truncate. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and sterile; overtly heteromorphic (but the sterile spikelets so reduced as to be confused with the glumes).
Inflorescence. Inflorescence of spicate main branches (a 3.5–6 cm raceme of spike-like racemes). Primary inflorescence branches 4–7. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary (apparently), or paired (really); secund; biseriate; shortly pedicellate, or sessile to subsessile (the sterile member); imbricate; consistently in long-and-short combinations (but not obviously so until the sterile spikelet is identified as such). The shorter spikelets sterile (reduced to a lanceolate, glabrous glume contiguous with the fertile spikelet). The longer spikelets hermaphrodite.
Female-sterile spikelets. The sterile spikelet of each pair reduced to an elongate glume.
Female-fertile spikelets. Spikelets unconventional (because of the reduced sterile spikelet continguous with the G1); 2–2.2 mm long; purple; abaxial; strongly compressed laterally; falling with the glumes. Rachilla terminated by a female-fertile floret.
Glumes two; relatively large; (the upper) long relative to the adjacent lemmas; dorsiventral to the rachis; awned (the G1 attenuate into a 2.5–4 mm awn); very dissimilar (both membranous, the G1 smaller, narrower, attenuate-aristate and asperulous, the G2 basally gibbous, verrucose and mucronate). Lower glume 3 nerved. Upper glume distinctly saccate (swelled out like a wallet); 7 nerved; probably becoming more or less prickly, or not prickly (?). 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 fully developed. The proximal incomplete florets male (with three stamens). The proximal lemmas carinate, subgibbous above; awnless (but rostrate); 3 nerved; decidedly exceeding the female-fertile lemmas; less firm than the female-fertile lemmas (membranous); not becoming indurated.
Female-fertile florets 1. Lemmas laterally compressed, acute; very thinly cartilaginous; smooth; not becoming indurated; entire; pointed; awnless; hairless (shiny); non-carinate (convex); having the margins lying flat on the palea; 3 nerved, or 5 nerved. Palea present; relatively long; somewhat thinner than the lemma (hyaline, less rigid); not indurated; 2-nerved; slightly 2-keeled. Lodicules present; 2; fleshy (lobed); glabrous. Stamens 3 (the anthers deeply sagittate basally and divaricate above, the thecae easily separating to simulate six stamens). Anthers about 1 mm long (relatively long, yellow, the filaments short and thick); not penicillate; without an apically prolonged connective. Ovary apically glabrous. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (0.9 mm long); elongated pyriform; not grooved; compressed laterally, or not noticeably compressed; glabrous. Hilum short. Embryo large; waisted. Endosperm hard.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much smaller and narrower). Intercostal zones with typical long-cells to exhibiting many atypical long-cells (many of them rather short, some very short). Mid-intercostal long-cells more or less isodiametric or somewhat irregular to rectangular; having markedly sinuous walls (coarsely sinuous). Microhairs present; elongated; clearly two-celled; panicoid-type. Stomata common (but confined to rows alongside the costae). Subsidiaries non-papillate; low to high dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. With numerous long, slender, cushion-based macrohairs and a few small prickles intercostally. Costal short-cells mostly conspicuously in long rows. Costal silica bodies present and well developed; panicoid-type; dumb-bell shaped and nodular.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll not Isachne-type; without arm cells; without fusoids. Midrib conspicuous; with one bundle only.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Boivinellinae (?). 1 species (P. madagascariensis).
Distribution, phytogeography, ecology. Madagascar.
References, etc. Morphological/taxonomic: Camus 1927b.
Special comments. Fruit data wanting.
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’.