The grass genera of the world
Habit, vegetative morphology. Coarse perennial; rhizomatous, or caespitose (with short thick rhizomes). Culms 50–200 cm high; herbaceous; unbranched above. Culm internodes solid. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; rolled (firm); without abaxial multicellular glands; not pseudopetiolate; rolled in bud. Ligule a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open, or contracted; when contracted, spicate to more or less irregular; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 5–9 mm long; lanceolate; compressed laterally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present (the hairs sometimes longer than half lemma length).
Glumes two; very unequal; shorter than the spikelets to about equalling the spikelets; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; pointed (acute); awnless; carinate; similar (papery or membranous). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1 (rarely with a second). Lemmas similar in texture to the glumes; not becoming indurated; entire; pointed; awnless; hairy (pilose at base), or hairless; carinate (slightly), or non-carinate; 1 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous; heavily vascularized. Stamens 3. Anthers 3–5.5 mm long. Ovary apically glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit linear, or ellipsoid. Hilum short. Pericarp free. Endosperm hard; without lipid. 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 absent. Long-cells markedly different in shape costally and intercostally (the costals narrower, more regularly rectangular); of similar wall thickness costally and intercostally (the walls thick), or differing markedly in wall thickness costally and intercostally (the costals thicker walled). Mid-intercostal long-cells having markedly sinuous walls (heavily pitted). Microhairs present; elongated; clearly two-celled; chloridoid-type (with long basal cells). Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 38–48(–60) microns long. Microhair basal cells 45 microns long. Microhairs 9.6–11.4 microns wide at the septum. Microhair total length/width at septum 3.9–5. Microhair apical cells 7–10(–12) microns long. Microhair apical cell/total length ratio 0.15–0.2. Stomata common; 22.5–30 microns long. Subsidiaries triangular, or dome-shaped (mostly, in C. longifolia). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs and not paired (some solitary); silicified. Intercostal silica bodies absent, or imperfectly developed; mostly saddle shaped. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present throughout the costal zones; mostly saddle shaped.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheath outlines even. 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 nodular in section; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (incorporated in the traversing colourless columns). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming figures (all the bundles with Is). Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Cytology. Chromosome base number, x = 10. 2n = 40.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Zoysieae; Sporobolinae (as a synonym of Sporobolus). 4 species.
Distribution, phytogeography, ecology. North America.
Species of open habitats. Dry or marshy pine barrens, inland dunes, sandy prairie.
Rusts and smuts. Rusts Puccinia.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • C. longifolia: Hitchcock and Chase (1950). • C. longifolia, abaxial epidermis of leaf blade: this project. • C. longifolia, TS Leaf blade: this project
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’.