Petriella Zotov
Sometimes referred to Ehrharta
Habit, vegetative morphology. Perennial; rhizomatous. Culms 1–40 cm high; woody and persistent, or herbaceous; unbranched above (but branching near the base). Culm nodes glabrous. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; auriculate. Leaf blades linear-lanceolate to ovate-lanceolate; narrow; 2–3 mm wide; flat, or folded; without cross venation; disarticulating from the sheaths (from the lower sheaths), or persistent; a fringed membrane; not truncate; to 0.5 mm long. Contra-ligule absent.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a single raceme, or paniculate; contracted; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; pedicellate; imbricate.
Female-fertile spikelets. Spikelets 3–5 mm long; compressed laterally; disarticulating above the glumes; with conventional internode spacings. Rachilla terminated by a female-fertile floret. Callus absent.
Glumes present; two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas (2.0–3.5 mm long); hairless; glabrous; pointed, or not pointed; awnless; carinate; very dissimilar, or similar (G1 or G2 may be rounded, truncate or acute at the tip). Lower glume shorter than the lowest lemma; much shorter than half length of lowest lemma; 1–3 nerved. Upper glume 3–5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 2 (the lemmas glabrous except at the base, without basal appendages, with prominent longitudinal veins but without transverse ribs); epaleate; sterile. The proximal lemmas awned (the apex acuminate, contracted into a short terminal awn); 0–7 nerved; more or less equalling the female-fertile lemmas to decidedly exceeding the female-fertile lemmas; decidedly firmer than the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (chartaceous); not becoming indurated; entire; blunt (truncate); awnless; hairless; glabrous; carinate; without a germination flap; 1–5 nerved. Palea present; relatively long (3/4 the length of the lemma); entire; awnless, without apical setae; thinner than the lemma (hyaline-membranous); not indurated; 1-nerved (i.e. the two veins contiguous); one-keeled. Lodicules present; 2; free; membranous; glabrous; at least slightly toothed; relatively heavily vascularized (cf. Ehrharta). Stamens 2. Anthers 1–1.5 mm long; without an apically prolonged connective. Ovary glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (2–3.5 mm long); ellipsoid; strongly compressed laterally. Hilum long-linear. Embryo small.
Taxonomy. Bambusoideae; Oryzodae; Ehrharteae.
Distribution, ecology, phytogeography. 2 species; New Zealand. Helophytic to mesophytic; species of open habitats; glycophytic. Mountains.
Antarctic. New Zealand.
Special comments. Seems scarcely distinguishable from Ehrharta and Tetrarrhena. Anatomical 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).