The grass genera of the world
Habit, vegetative morphology. Perennial. Culms herbaceous. Leaf blades without cross venation.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; contracted (panicle dense); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets pedicellate; not in distinct long-and-short combinations.
Female-fertile spikelets. Spikelets compressed laterally. Rachilla terminated by a female-fertile floret.
Glumes two; very unequal; long relative to the adjacent lemmas; the upper awned; very dissimilar (G1 short and awnless, G2 bilobed with the median nerve excurrent into an awn). Upper glume obscurely 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; paleate; male. The proximal lemmas awned (bilobed, the median nerve excurrent between).
Female-fertile florets 1. Lemmas less firm than the glumes (thinly membranous, by contrast with the firmly membranous G2); not becoming indurated; incised; 2 lobed; awned. Awns 1; median; from a sinus. Palea present. Stigmas 2.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells more or less markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (the walls of medium thickness). Intercostal zones exhibiting many atypical long-cells (mainly in the mid-intercostal regions). Mid-intercostal long-cells rectangular; having markedly sinuous walls (the sinuosity fairly coarse to fine, irregular). Microhairs present; elongated; clearly two-celled; panicoid-type. Stomata common. Subsidiaries non-papillate; low dome-shaped to triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells fairly common (but not to be confused with small prickles); not paired (seemingly solitary); not obviously silicified. With numerous very small intercostal prickles. Costal short-cells conspicuously in long rows (but the short-cells often quite long). Costal silica bodies present and well developed; panicoid-type; cross shaped and dumb-bell shaped; sharp-pointed and not sharp-pointed.
Transverse section of leaf blade, physiology. C4. The anatomical organization conventional. XyMS+. PCR sheath outlines uneven. PCR sheath extensions absent. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells (these columns infrequent, of small cells, one cell wide). Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans (the fans very large, usually simple but occasionally with one or two small clourless cells contiguous internally, rarely these forming a linking column). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present (with a few of the primaries); nowhere forming figures (the sclerenchyma scanty). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Melidininae. 1 species.
Distribution, phytogeography, ecology. Tropical Africa: Annobon Is.
References, etc. Morphological/taxonomic: Butzin 1971. Leaf anatomical: this project.
Special comments. Fruit data wanting.
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’.