Pommereulla L.f.
Habit, vegetative morphology. Perennial; stoloniferous. Culms 5–15 cm high; herbaceous. Leaf blades linear; narrow; 2–3 mm wide; flat, or folded; exhibiting multicellular glands abaxially. The abaxial leaf blade glands on the blade margins. Leaf blades without cross venation; disarticulating from the sheaths (apparently); a fringed membrane to a fringe of hairs (a pubescent ridge).
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a single raceme (the raceme occasionally forked). Rachides flattened. Inflorescence espatheate (but the raceme usually partially enclosed in the uppermost, spathe-like sheath); not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary (close or distant); secund (?); pedicellate.
Female-fertile spikelets. Spikelets more or less morphologically ‘conventional’ (but the lemmas spirally arranged, forming an inverted cone, and changing form acropetally); 8 mm long; compressed dorsiventrally; disarticulating above the glumes; not disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Callus long (at the base of the lowermost floret); pointed.
Glumes two; (the upper) about equalling the spikelets (the lower shorter); (the upper) long relative to the adjacent lemmas; awnless; non-carinate; similar (membranous, persistent, amplexicaul at the base, the G2 larger). Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets both distal and proximal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets with proximal incomplete florets. The proximal incomplete florets 2 (fan-shaped, embracing the fertile lemmas); epaleate; sterile. The proximal lemmas 4-lobed, the lobes acute to short-awned, inner lobes narrower, the lemma with a slender awn from middle of back; awned (dorsally, and mucronate or aristulate from the four lobes); 7–9 nerved; more or less equalling the female-fertile lemmas to decidedly exceeding the female-fertile lemmas.
Female-fertile florets 2–3. Lemmas conspicuously non-distichous; similar to the proximal lemmas, becoming smaller acropetally; incised; 4 lobed (the outer lobes much longer); deeply cleft; awned. Awns 1; median; dorsal; from well down the back (from about middle); non-geniculate; hairless; much shorter than the body of the lemma. Lemmas hairy; non-carinate; 7–9 nerved. Palea present; relatively long (flat); entire to apically notched; awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; glabrous; not or scarcely vascularized. Stamens 3. Anthers short; not penicillate; without an apically prolonged connective. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit ellipsoid. Embryo with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal. Intercostal papillae not over-arching the stomata; commonly consisting of one oblique swelling per cell (sometimes cells with two). Mid-intercostal long-cells rectangular; having markedly sinuous walls (and outer walls pitted). Microhairs present; more or less spherical; clearly two-celled (the basal cell sunken); chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhair basal cells 6–9 microns long (but sunken). Microhair total length/width at septum 1.3. Microhair apical cell/total length ratio 0.6. Stomata common. Subsidiaries markedly triangular. Intercostal short-cells fairly common; in cork/silica-cell pairs and not paired (some solitary); silicified. Intercostal silica bodies absent to imperfectly developed; rounded (narrowly oval), or crescentic. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; saddle shaped (to rectangular); not sharp-pointed.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted both abaxially and adaxially. PCR sheath extensions absent. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells. Leaf blade with distinct, prominent adaxial ribs (towards midrib), or adaxially flat (outside); with the ribs more or less constant in size (low). Midrib conspicuous; having a conventional arc of bundles (large median, several small strands either side). Bulliforms present in discrete, regular adaxial groups (including a large, median group in a groove over midrib); associated with colourless mesophyll cells to form deeply-penetrating fans (these linked to the abaxial epidermis by girders of colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (nearly all bundles). Sclerenchyma forming a hypodermal plate adaxially in midrib.
Taxonomy. Chloridoideae; main chloridoid assemblage (‘Pommereulleae’).
Distribution, ecology, phytogeography. 1 species; eastern Asia. Species of open habitats.
Paleotropical. Indomalesian. Indian.
References, etc. Leaf anatomical: Metcalfe 1960; Van den Borre 1994.
Special comments. Fruit data wanting.
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).