The grass genera of the world
Type species: Type: P. muelleri (Hack.) S.T.Blake.
Habit, vegetative morphology. Perennial; stoloniferous, or caespitose, or decumbent. Culms 10–45 cm high; branched above. Culm nodes hairy. Culm leaf sheaths rounded. Culm internodes solid. Young shoots culm branches intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear to ovate; narrow; 2–4 mm wide; not pseudopetiolate; without cross venation; disarticulating from the sheaths; rolled in bud. Ligule a fringe of hairs.
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; hermaphrodite, or hermaphrodite and sterile (then the lowest spikelets reduced). Not viviparous.
Inflorescence. Inflorescence a single raceme (contracted, spike-like, the spikelets spiralled); contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; not two-ranked (spiralled); pedicellate (the pedicels short, persistent). Pedicel apices oblique, or discoid.
Female-fertile spikelets. Spikelets 7–12 mm long; lanceolate; abaxial; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret; hairless. Hairy callus present. The callus hairs white (very conspicuous, long).
Glumes two; more or less equal; long relative to the adjacent lemmas; dorsiventral to the rachis; hairy (with dense white hairs); pointed (subulate-acuminate); awned (acuminate into the short subule), or awnless (acuminate, hardly truly awned); non-carinate; very dissimilar (the lower membranous, flat on back and not bearded, the upper convex and hardened towards the base, with a dense narrow beard of long white submarginal hairs on each side below). Lower glume two-keeled (above); 5–7 nerved. Upper glume 9–13 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 reduced. The proximal incomplete florets male. The proximal lemmas gibbous below; awnless; 7 nerved; exceeded by the female-fertile lemmas to decidedly exceeding the female-fertile lemmas.
Female-fertile florets 1. Lemmas similar in texture to the glumes; smooth to striate; not becoming indurated (L2 thinly rigid. cf. Thyridolepis, contrast Neurachne); yellow in fruit; entire; pointed; awnless; hairy, or hairless; non-carinate; having the margins lying flat on the palea; with a clear germination flap; 3–7 nerved. Palea present (acuminate); relatively long; apically notched; awnless, without apical setae; textured like the lemma; indurated; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers about 2.5 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles fused, or free to their bases. Stigmas 2 (and 2 styles); red pigmented.
Fruit, embryo and seedling. Fruit small; compressed dorsiventrally. Hilum short. Embryo large; waisted. Endosperm containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with a negligible mesocotyl internode.
First seedling leaf with a well-developed lamina. The lamina broad; curved.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; 51–63 microns long; 9–9.9 microns wide at the septum. Microhair total length/width at septum 5.2–7. Microhair apical cells 28.5–33 microns long. Microhair apical cell/total length ratio 0.52–0.59. Stomata common; 27–36 microns long. Guard-cells overlapping to flush with the interstomatals (slightly overlapping). Intercostal short-cells common; in cork/silica-cell pairs; silicified. Many prickles present, mostly reduced to their bases. Crown cells present (or at least, many structures (obviously reduced prickles) approaching these). Costal short-cells conspicuously in long rows and neither distinctly grouped into long rows nor predominantly paired (mostly pairs and short rows, but some long rows - quite a mixture). Costal silica bodies panicoid-type; mostly cross shaped, butterfly shaped, and dumb-bell shaped (short); not sharp-pointed.
Transverse section of leaf blade, physiology. C4. The anatomical organization unconventional. Organization of PCR tissue Alloteropsis type. Biochemical type NADPME; XyMS (the inner sheath of large, thin walled cells is PCR, but there is another sheath of smaller, sparsely chlorenchymatous cells outside it. c.f.Alloteropsis, Neurachne). PCR sheath outlines even. PCR sheath extensions present. Maximum number of extension cells 1. PCR cells with a suberised lamella. PCR cell chloroplasts with well developed grana; centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs (with broad, flat-topped adaxial ribs, each including several vascular bundles); with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only to having a conventional arc of bundles (with a small bundle beneath each bulliform group). Bulliforms present in discrete, regular adaxial groups; in simple fans, or in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent (combining broad abaxial girders with adaxial strands). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 9. 2n = 36. 4 ploid.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Neurachneae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Neurachninae. 1 species.
Distribution, phytogeography, ecology. Northern Australia.
Xerophytic; species of open habitats. Dry grassland.
References, etc. Morphological/taxonomic: Blake 1972b. Leaf anatomical: Hattersley et al. 1982.
Illustrations. • General morphology (P. muelleri): Blake, 1972. • P. muelleri: Gardner, 1952. • Infloresence detail with opened spikelet (P. muelleri). Paraneurachne muelleri. One spikelet partly opened to show the lower, male-only floret and the upper, hermaphrodite one. • Spikelet of P. muelleri. • Spikelet displaying lower floret details (P. muelleri). Paraneurachne muelleri. Male flower of proximal floret, palea removed, showing fleshy lodicules. Upper, hermaphrodite floret behind (stigmas showing). • Lower, male-only floret of P. muelleri. Paraneurachne muelleri. Flimsy, reduced palea and large stamens, enclosed in the proximal lemma. • Gynoecium (P. muelleri). • P. muelleri, abaxial epidermis of leaf blade: this project. • P. muelleri, TS of leaf blade detail: 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: 13th November 2017. delta-intkey.com/grass’.