Polypogon Desf.
From the Greek polys (many) and pogon (beard), referring to the whiskery panicle.
Including Chaetotropis Kunth, Nowodworskya Presl., Raspailia Presl., Santia Savi
Habit, vegetative morphology. Annual, or perennial; stoloniferous, or caespitose. Culms 2–120 cm high; herbaceous; branched above, or unbranched above. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Sheath margins free. Leaf blades linear to linear-lanceolate; narrow; 1–10 mm wide; setaceous (e.g., sometimes in P. tenellus), or not setaceous; flat (usually), or rolled (P. tenellus); without cross venation; persistent; rolled in bud; an unfringed membrane; truncate, or not truncate; 2–15 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant (e.g., P. tenellus and P. monspeliensis at least sometimes exhibiting numerous small branches of abortive spikelets), or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile. Plants inbreeding; exposed-cleistogamous (presumably, in P. tenellus, P. griquensis), or chasmogamous.
Inflorescence. Inflorescence paniculate; bristly, contracted (usually, more ore or less), or open to contracted (e.g., P. viridis); more or less ovoid, or spicate, or more or less irregular; without capillary branchlets. Primary inflorescence branches borne distichously. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 1.5–3 mm long; somewhat compressed laterally; falling with the glumes (and the pedicel, or part of it, in most or all species). Rachilla terminated by a female-fertile floret. Hairy callus present (comprising the disarticulating part the base of the spikelet and the base of the glumes, in P. tenellus), or absent (usually). Callus short to long (represented by that part of the pedicel which falls with the spikelet).
Glumes present; two; relatively large; more or less equal; exceeding the spikelets; long relative to the adjacent lemmas; hairless (usually hispid or hispid and ciliolate), or hairy (P. tenellus, P. australis); usually scabrous; pointed (entire to bilobed); usually conspicuously awned (apically or from a notch), or awnless (e.g. P. viridis (semiverticillatus)); carinate to non-carinate; similar (chartaceous, usually scabrid, rarely hairy). Lower glume 1 nerved. Upper glume 1(–3) nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); smooth (shiny); not becoming indurated; entire to incised (truncate, finely toothed via excurrent nerves); not deeply cleft; awnless, or mucronate, or awned (usually). Awns when present (i.e. usually), 1, or 3; median (usually), or median and lateral (lateral nerves sometimes excurrent as short awns or mucros); from a sinus, or apical, or dorsal (conspicuously so only in P. tenellus and perhaps in P. australis); when dorsal, from near the top (usually ‘subterminal’), or from well down the back (from slightly above the middle in P. tenellus); non-geniculate (usually), or geniculate (P. tenellus and perhaps P. australis); hairless; much shorter than the body of the lemma to about as long as the body of the lemma (usually), or much longer than the body of the lemma (and much exceeding the glume awns, only in P. tenellus); entered by one vein; deciduous (usually), or persistent (P. tenellus). Awn bases twisted (P. tenellus), or not twisted; not flattened. Lemmas hairless; glabrous; non-carinate; without a germination flap; 5 nerved; with the nerves non-confluent. Palea present; relatively long, or conspicuous but relatively short (Chaetotropis, e.g. P. chilensis); tightly clasped by the lemma; entire (truncate), or apically notched; awnless, without apical setae, or with apical setae to awned (e.g., P. australis); thinner than the lemma to textured like the lemma; not indurated (hyaline); inconspicuously 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 2, or 3 (usually?), or 1 (in P. tenellus, P. griquensis). Anthers 0.2–0.6 mm long; not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea (usually), or free from both lemma and palea (e.g. P. viridis); small; fusiform (Chaetotropis), or ellipsoid; longitudinally grooved (usually), or not grooved (e.g. P. viridis); not noticeably compressed. Hilum short. Embryo large (rarely), or small; not waisted. Endosperm liquid in the mature fruit, or 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. 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. Mid-intercostal long-cells rectangular, or fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common; (31.5–)33–36(–37.5) microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare; when present, not paired (mostly solitary); not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (mostly), or horizontally-elongated smooth (a few); 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, or ‘nodular’ in section (rarely); with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in the furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present, or absent (rarely); nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Culm anatomy. Culm internode bundles in one or two rings.
Phytochemistry. Leaves without flavonoid sulphates (1 species).
Cytology. Chromosome base number, x = 7. 2n = 14, 28, 42, 50, and 60 (not known for P. tenellus). 2, 4, 6, 7, and 8 ploid. Chromosomes ‘large’.
Taxonomy. Pooideae; Poodae; Aveneae. Beard grasses.
Distribution, ecology, phytogeography. 18 species; Mediterranean, southwest Asia. Commonly adventive. Helophytic to mesophytic; species of open habitats; halophytic, or glycophytic. In moist ground.
Holarctic, Paleotropical, Neotropical, Cape, Australian, and Antarctic. Boreal and Tethyan. African and Indomalesian. Euro-Siberian, Eastern Asian, and Atlantic North American. Macaronesian, Mediterranean, and Irano-Turanian. Saharo-Sindian, Sudano-Angolan, Namib-Karoo, and Ascension and St. Helena. Indian, Indo-Chinese, and Papuan. Caribbean, Central Brazilian, Pampas, Andean, and Fernandezian. South-West Australian. Antarctic and Subantarctic. European. Canadian-Appalachian and Central Grasslands. Somalo-Ethiopian. South Temperate Oceanic Islands.
Hybrids. Intergeneric hybrids with Agrostis (×Agropogon P. Fourn.).
Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia graminis and Puccinia coronata. Smuts from Tilletiaceae. Tilletiaceae — Entyloma.
Economic importance. Significant weed species: P. monspeliensis, P. viridis.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • General aspect, spikelet. • General aspect. • General aspect
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).
