The grass genera of the world
Habit, vegetative morphology. Perennial; caespitose. Culms 30–100 cm high; herbaceous; unbranched above; somewhat tuberous. Culm nodes glabrous. Young shoots intravaginal. Leaves mostly basal; non-auriculate. Leaf blades narrow; about 5 mm wide; not setaceous (tending to subulate); flat, or folded; without cross venation; persistent. Ligule a fringed membrane.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open; with capillary branchlets; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets unconventional (as a eu-panicoid, because either a glume or the L1 is missing); about 4.8 mm long; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes one per spikelet (if the second organ is assumed to be the L1); shorter than the adjacent lemmas to long relative to the adjacent lemmas; hairy; not pointed; awnless; non-carinate. Upper glume (as interpreted here) 5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1 (hairy); epaleate; sterile. The proximal lemmas awnless; 5 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 flat, becoming hyaline towards the tip; similar in texture to the glumes; smooth; becoming indurated; brown in fruit; entire; pointed; awnless; hairless (but ciliate on the upper edges); non-carinate; having the margins lying flat on the palea (unusual in not gripping it); with a clear germination flap; 5 nerved. Palea present; relatively long; gaping; entire; awnless, without apical setae; textured like the lemma; 2-nerved; keel-less. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate. Ovary apically glabrous. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (2.5 mm long); ellipsoid. Hilum short. Embryo large; not waisted.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present (but very scarce); panicoid-type; 39–46.5 microns long; 9–9.6 microns wide at the septum. Microhair total length/width at septum 4.3–4.8. Microhair apical cells 24–27 microns long. Microhair apical cell/total length ratio 0.58–0.62. Stomata common; 34.5–36 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs and not paired; not silicified. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; cross shaped and dumb-bell shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C4. The anatomical organization unconventional (somewhat, in that the minor vascular bundles are scattered across the thickish blade portions between the major bundles). Organization of PCR tissue approaching the Arundinella type. XyMS+. Mesophyll without circular cells (but the PCR cells of numerous tiny bundles could be mistaken for these). Leaf blade nodular in section; with the ribs more or less constant in size. Midrib conspicuous; having a conventional arc of bundles (large median, small laterals); with colourless mesophyll adaxially. Bulliforms not present in discrete, regular adaxial groups (Ammophila-type groups of small cells in the furrows, save for the midrib hinges). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures. Sclerenchyma all associated with vascular bundles.
Phytochemistry. Leaves without flavonoid sulphates (1 species).
Cytology. Chromosome base number, x = 10. 2n = 40. 4 ploid.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paspaleae; Otachyriinae. 1 species.
Distribution, phytogeography, ecology. Warm America, West Indies.
Species of open habitats. Savanna.
References, etc. Morphological/taxonomic: Parodi 1969. Leaf anatomical: this project.
Illustrations. • L. lanatum, as Milium: Kunth (1835). • L. lanatum: Hitchcock , W.I. Grasses (1936).. • L. lanatum: Nicora & Rúgolo de Agrasar (1987)
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’.