The grass genera of the world
Including Schmidtia Tratt., Wilibalda Roth
Habit, vegetative morphology. Dwarf annual; decumbent. Culms 2–10 cm high; herbaceous. Leaves non-auriculate. Sheath margins joined. Sheaths inflated. Leaf blades linear (usually recurved); narrow; about 1 mm wide; flat, or folded; without cross venation. Ligule present; an unfringed membrane; 1–1.5 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence paniculate (subtended by the expanded sheath of the upper leaf, the branches in compact, globular fascicles); contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent (?). Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets unconventional (in lacking glumes); 0.75–1.5 mm long; not noticeably compressed; disarticulating under the lemma. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus short.
Glumes absent. Spikelets with female-fertile florets only.
Female-fertile florets 1. Lemmas not becoming indurated (membranous or hyaline); entire; pointed; awned. Awns 1; median; apical (from the caudate- or aristate-acuminate lemma); non-geniculate; entered by one vein. Lemmas hairless (but ciliate on the keel); carinate; without a germination flap; 1 nerved. Palea present; conspicuous but relatively short; not indurated (membranous); 2-nerved; 2-keeled. Lodicules absent. Stamens 2. Anthers 0.3–0.4 mm long. Ovary apically glabrous. Styles free to their bases (very long). Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1.5 mm long). Hilum short (oval). Embryo small. Endosperm hard; without lipid; containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells differing markedly in wall thickness costally and intercostally. Intercostal zones with typical long-cells (but seemingly lacking short-cells). Mid-intercostal long-cells having straight or only gently undulating walls. Microhairs absent. Stomata common. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal zones seemingly without short-cells (in the material seen). Costal silica bodies absent.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Leaf blade adaxially flat. Midrib conspicuous (mainly by its position); with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms not present in discrete, regular adaxial groups (apart from midrib hinges). Many of the smallest vascular bundles unaccompanied by sclerenchyma (all bundles unaccompanied by sclerenchyma, in the material seen).
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Chromosomes large.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Coleanthinae. 1 species.
Distribution, phytogeography, ecology. North temperate.
Helophytic to mesophytic (in dried up lakes and reservoirs, at pond margins); glycophytic.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia graminis.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • C. subtilis: Lamson-Scribner (1890). • C. subtilis: Hitchcock and Chase (1950)
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: 13th November 2017. delta-intkey.com/grass’.