Pogonatherum P. Beauv.
From the Greek pogon (beard) and ather (awns on an ‘ear of corn’), referring to the beardlike appearance of inflorescences resulting from fine awns.
Including Homoplitis Trin., Pogonopsis Presl
Habit, vegetative morphology. Delicate perennial; caespitose, or decumbent. Culms 12–60 cm high; branched above. Culm nodes hairy, or glabrous. Culm internodes solid. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; usually flat; pseudopetiolate; without cross venation; persistent; a fringed membrane.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets (in the sessile spikelets). The spikelets of sexually distinct forms on the same plant; hermaphrodite and female-only (hermaphrodite-sessile and female-pedicelled); more or less homomorphic (the pedicelled slightly smaller).
Inflorescence. Inflorescence a solitary, spicate, pedunculate, axillary ‘raceme’; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ‘racemes’; solitary; disarticulating; disarticulating at the joints. Spikelets paired; not secund; sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations. The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets female-only.
Female-fertile spikelets. Spikelets spikelets small; compressed laterally; falling with the glumes (the pedicelled falling from its pedicel, the sessile falling with the internode and pedicel). Rachilla terminated by a female-fertile floret. Hairy callus present, or absent. Callus blunt.
Glumes two; more or less equal; long relative to the adjacent lemmas; hairy, or hairless; without conspicuous tufts or rows of hairs; (the upper) awned (with a capillary awn from the mid-nerve); very dissimilar (G1 cartilaginous, rounded on the back and truncate, G2 compressed-keeled and awned). Lower glume strongly convex on the back; not pitted; relatively smooth; 0–1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; male, or sterile. The proximal lemmas 0 nerved, or 1 nerved; not becoming indurated.
Female-fertile florets 1. Lemmas less firm than the glumes (thinly membranous to hyaline); not becoming indurated; incised; 2 lobed; deeply cleft to not deeply cleft (to 1/3 to 1/2 its length); awned. Awns 1; median; from a sinus; geniculate; much longer than the body of the lemma (filiform). Lemmas hairless; non-carinate; 1 nerved. Palea present; nerveless. Lodicules absent. Stamens 1–2. Anthers not penicillate. Ovary glabrous. Styles fused. Stigmas 2.
Fruit, embryo and seedling. Fruit small; compressed dorsiventrally (flattened on the front). Hilum short. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae over-arching the stomata; several per cell (often slightly irregular in shape). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 24–27(–30) microns long; (3.6–)4.8–5.4 microns wide at the septum. Microhair total length/width at septum 4.4–7.5. Microhair apical cells (10.5–)15–16.5 microns long. Microhair apical cell/total length ratio 0.5–0.63. Stomata common; (18–)21–22.5(–24) microns long. Subsidiaries triangular (or obscured by the papillae). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies acutely-angled (very acutely rectangular); sharp-pointed.
Transverse section of leaf blade, physiology. C4; XyMS–. Mesophyll with radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs, or ‘nodular’ in section; with the ribs more or less constant in size. Midrib conspicuous, or not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (and in irregular groups); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. 2n = 20.
Taxonomy. Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae.
Distribution, ecology, phytogeography. 3 species; India to Japan.
Holarctic, Paleotropical, and Australian. Boreal and Tethyan. Indomalesian. Eastern Asian. Irano-Turanian. Indian, Indo-Chinese, Malesian, and Papuan. North and East Australian. Tropical North and East Australian.
Rusts and smuts. Rusts — Puccinia.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
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).