The grass genera of the world

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L. Watson and M. J. Dallwitz

Phalaris L.

Phalaris: the name for members of this genus in both ancient and modern Greek. Perhaps via phalos (shining), referring to the glossy lemma, or more likely via the alternative sense of the word (the ridge of a helmet), this describing beautifully the glabrous, keel-winged glumes.

Including Baldingera Gaertn., Meyer & Scherb., Digraphis Trin., Endallex Raf., Phalaridantha St-Lager, Phalaroides Wolf, Typhoides Moench

Habit, vegetative morphology. Annual, or perennial; some species reedlike; rhizomatous, or caespitose, or decumbent. Culms 10–200 cm high; herbaceous; unbranched above; tuberous, or not tuberous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear to linear-lanceolate; broad, or narrow; 2–20 mm wide; flat; not pseudopetiolate; without cross venation; persistent; rolled in bud. Ligule present; an unfringed membrane; truncate, or not truncate; 2–12 mm long.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant (rarely), or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile (clusters of one fertile and several deformed-sterile in P. paradoxa and P. coerulescens). Plants outbreeding and inbreeding.

Inflorescence. Inflorescence a false spike, with spikelets on contracted axes, or paniculate; open (rarely), or contracted; when contracted capitate, or more or less ovoid, or spicate, or more or less irregular. Primary inflorescence branches borne distichously, or inserted all around the main axis. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes disarticulating, or persistent; when disarticulating, falling entire (the clusters falling in P. paradoxa and P. coerulescens). Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 3.5–9.5 mm long; strongly compressed laterally; disarticulating above the glumes, or falling with the glumes, or not disarticulating. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; more or less equal; about equalling the spikelets to exceeding the spikelets; long relative to the adjacent lemmas; pointed; awnless; carinate; with the keel conspicuously winged, or without a median keel-wing; similar (papery). Lower glume 1–5 nerved. Upper glume 1–5 nerved. Spikelets usually with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1, or 2; usually epaleate; usually sterile. The proximal lemmas awnless; exceeded by the female-fertile lemmas; less firm than the female-fertile lemmas (reduced to scales); not becoming indurated.

Female-fertile florets 1(–2). Lemmas decidedly firmer than the glumes; becoming indurated; entire; pointed; awnless; hairy, or hairless; carinate; 5 nerved. Palea present; relatively long; entire to apically notched; awnless, without apical setae; thinner than the lemma to textured like the lemma; indurated, or not indurated; 1-nerved, or 2-nerved; keel-less. Lodicules present; 2; free; membranous; glabrous; not toothed. Stamens 3. Anthers 1.2–6 mm long; not penicillate. Ovary glabrous. Styles fused, or free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small; compressed laterally. Hilum long-linear. Embryo large (up to a third of the grain length), or small; not waisted. Endosperm hard; with lipid; containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.

Seedling with a long mesocotyl; with a loose coleoptile, or with a tight coleoptile. First seedling leaf with a well-developed lamina. The lamina narrow; erect; 3–5 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 (fairly thin walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common; (30–)33–39(–42) microns long. Subsidiaries low dome-shaped, or parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells common (rarely), or absent or very rare (absent); in cork/silica-cell pairs, or not paired; silicified, or not silicified. Intercostal silica bodies when present, rounded (oval). Costal short-cells neither distinctly grouped into long rows nor predominantly paired (usually), or conspicuously in long rows and neither distinctly grouped into long rows nor predominantly paired (P. angusta). Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth, or rounded (or cuboid - varying from species to species), or ‘panicoid-type’ (occasionally); occasionally cross shaped, or butterfly shaped; not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. PBS cells without a suberised lamella. Mesophyll with radiate chlorenchyma (rarely), or with non-radiate chlorenchyma. Leaf blade adaxially flat; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present, or absent; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Phytochemistry. Tissues of the culm bases with little or no starch. Fructosans predominantly long-chain. Leaves without flavonoid sulphates (1 species).

Cytology. Chromosome base number, x = 6 and 7. 2n = 12, 14, 28, 35, 42, and 56 (and aneuploids). 2, 4, 6, and 8 ploid (and aneuploids). Chromosomes ‘large’. Haploid nuclear DNA content 1.7–3.7 pg (13 species, mean 2.4). Mean diploid 2c DNA value 5.8 pg (9 species, (2.8-)3.5–9.0). Nucleoli disappearing before metaphase.

Taxonomy. Pooideae; Poodae; Aveneae. Phalaris, Canary grasses.

Distribution, ecology, phytogeography. 22 species; North temperate, South America. Commonly adventive. Helophytic, or mesophytic; species of open habitats. In weedy places, damp soils and swamps.

Holarctic, Paleotropical, Neotropical, and Antarctic. Boreal, Tethyan, and Madrean. African and Indomalesian. Arctic and Subarctic, Euro-Siberian, Eastern Asian, Atlantic North American, and Rocky Mountains. Macaronesian, Mediterranean, and Irano-Turanian. Saharo-Sindian and Sudano-Angolan. Indian. Caribbean, Pampas, and Andean. Patagonian. European and Siberian. Canadian-Appalachian, Southern Atlantic North American, and Central Grasslands. Somalo-Ethiopian.

Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia graminis, Puccinia coronata, and Puccinia striiformis. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae — Entyloma and Tilletia. Ustilaginaceae — Ustilago.

Economic importance. Significant weed species: P. aquatica, P. arundincacea, P. brachystachys, P. canariensis, P. minor, P. paradoxa. Cultivated fodder: P. arundinacea, P. aquatica. Important native pasture species: P. arundinacea. Grain crop species: P. canariensis (Canary grass), mainly for bird seed.

References, etc. Morphological/taxonomic: Anderson 1961. Leaf anatomical: Metcalfe 1960; this project.

Illustrations. • General aspect (P. aquatica): Gibbs Russell et al., 1990. • P. canariensis, general aspect: Eng. Bot. (1872). • P. canariensis: Gardner, 1952. • P. arundinacea (as Digraphis): Eng. Bot. (1872). • Inflorescence of P. aquatica. • Spikelet close-up of P. aquatica. Phalaris aquatica. Keel-winged glumes exceeding the spikelet and concealing the short proximal lemms. Hairy young female-fertile lemma. • Close-up of glumes of P. aquatica. Phalaris aquatica. Keel-winged glumes. • Infloresecnce detail of P. paradoxa. • Spikelet of P. paradoxa. • Abaxial epidermis of leaf blade (P. aquatica). • Transverse section of leaf blade (P. aquatica). • Pollen antigens. • Pollen antigens: cross-reactions against anti-Lolium serum. • Pollen antigens: cross-reactions against anti-Lolium serum. • Heat stable pollen antigens (allergens): cross-reactions against anti-Lolium serum

The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. This is much more easily achieved using 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, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).

Cite this publication as: ‘Watson, L., 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: 7th December 2015.’.