Pentapogon R.Br.
From the Greek pente (five) and pogon (beard), referring to five-awned lemmas.
Habit, vegetative morphology. Annual, or perennial; caespitose. Culms 20–60 cm high; herbaceous. Culm nodes hairy. Culm internodes hollow. Leaves auriculate, or non-auriculate. Leaf blades narrow; not setaceous (inrolled); without cross venation; persistent; an unfringed membrane; truncate, or not truncate; 0.5–2 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open (the branches scabrid). 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 5–15 mm long; compressed laterally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present.
Glumes two; very unequal to more or less equal; (the longer) exceeding the spikelets; (the longer) long relative to the adjacent lemmas (exceeding them); hairless (scabrid, especially on the keels); pointed; shortly awned, or awnless; carinate; similar (membranous, acuminate). Lower glume 1(–3) nerved. Upper glume 3(–5) nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (leathery); becoming indurated to not becoming indurated; incised; 4 lobed; deeply cleft (deeply incised into 4 lanceolate, awn-tipped lobes, with a long median awn); awned. Awns 5; median and lateral; the median different in form from the laterals; dorsal; from near the top (i.e., arising just behind the sinus); geniculate; hairless (scabrid); much longer than the body of the lemma; entered by one vein. The lateral awns shorter than the median (straight, slender). Lemmas hairless; glabrous; non-carinate; 5 nerved. Palea present; relatively long, or conspicuous but relatively short, or very reduced; tightly clasped by the lemma; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; not toothed. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small; not noticeably compressed. Hilum short. Embryo small. Endosperm liquid in the mature fruit (Clayton and Renvoize 1986).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (but the costals nuch smaller); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular to fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous and horizontally-elongated smooth, or rounded (a few); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade ‘nodular’ in section; 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 simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present, or absent; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Taxonomy. Pooideae; Poodae; Aveneae.
Distribution, ecology, phytogeography. 1 species; Australia, Tasmania. Mesophytic, or xerophytic; glycophytic. Open woodland.
Australian. North and East Australian. Temperate and South-Eastern Australian.
References, etc. Leaf anatomical: Metcalfe 1960 and this project.
Illustrations. • Inflorescence detail. • Spikelet. • Spikelet base
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).
