The grass genera of the world
Habit, vegetative morphology. Delicate annual; stoloniferous. Culms herbaceous. Leaves not basally aggregated; non-auriculate. Leaf blades narrowly elliptic; flimsy; relatively broad; 3–7 mm wide (and about 1.5–4 cm long); flat; without cross venation. Ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate (small, scanty, terminating the leafy branches); open; with capillary branchlets; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; not in distinct long-and-short combinations.
Female-fertile spikelets. Spikelets unconventional (said to have two lemmas, both lacking paleas); 2.7 mm long; not noticeably compressed to compressed dorsiventrally; disarticulating above the glumes (the glumes persistent); not disarticulating between the florets. Rachilla terminated by a female-fertile floret (?). Hairy callus absent.
Glumes two; more or less equal; about equalling the spikelets; long relative to the adjacent lemmas; hairless; awnless; non-carinate (lanceolate, round-backed); similar (thinly membranous). Lower glume 5–7 nerved. Upper glume 5–7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas lanceolate; awnless; 7–9 nerved; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas not becoming indurated (membranous); entire; pointed, or blunt; awnless; hairless; non-carinate; 7–9 nerved. Palea absent (unless the L2 is a many-nerved palea). Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small (1.5 mm long); fusiform; compressed dorsiventrally. Hilum short (very shortly linear). Embryo large (about a third of the fruit length). Endosperm containing compound starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Intercostal zones exhibiting many atypical long-cells. Mid-intercostal long-cells having straight or only gently undulating walls. Microhairs absent (but present adaxially); panicoid type. Stomata absent or very rare. Intercostal short-cells absent or very rare. Costal silica bodies acutely-angled (cuboid); sharp-pointed (square to rectangular).
Transverse section of leaf blade, physiology. C3 (seemingly with only two layers of mesophyll, the cells of upper layer irregularly lobed, those of the lower forming a palisade).
Special diagnostic feature. Plants of wet places, the leaves remarkably thin and delicate.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Isachneae. Soreng et al. (2015): Micrairoideae; Hubbardieae. 1 species (H. heptaneuron).
Distribution, phytogeography, ecology. Southern India.
Helophytic (discovered in wet soil and high humidity, in the spray from a waterfall).
References, etc. Leaf anatomical: Clifford 1967.
Special comments. Extinct?.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The 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. Version: 11th December 2017. delta-intkey.com/grass’.