The grass genera of the world
Habit, vegetative morphology. Annual. Culms 30–90 cm high; herbaceous. Culm nodes hairy. Plants unarmed. Leaf blades lanceolate; narrow; flat; without cross venation. Ligule a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; contracted; spicate; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets pedicellate (the pedicels accrescent to the axes).
Female-fertile spikelets. Spikelets morphologically conventional; 7–10 mm long; purplish; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus short; blunt.
Glumes two; very unequal; (the upper) long relative to the adjacent lemmas (as long as the spikelet); hairy (the G1 usually sparsely hairy), or hairless (glabrous); pointed; awned (the G1 with a 4–5 mm awn, the G2 pointed or continued into a bristle); thin-membranous. Lower glume 3 nerved. Upper glume 3 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. Palea of the proximal incomplete florets fully developed (becoming conspicuously indurated, thickened between the keels). The proximal incomplete florets sterile. The proximal lemmas awnless (pointed); 5–7 nerved.
Female-fertile florets 1. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (thinly leathery); not becoming indurated; incised; deeply cleft; awned. Awns 3; median and lateral; the median different in form from the laterals; from a sinus; geniculate; much longer than the body of the lemma. The lateral awns shorter than the median (straight). Lemmas hairy. The hairs in tufts (on the lemma margins and at the awn base); in transverse rows. Lemmas non-carinate; 5 nerved. Palea present; relatively long; apically notched; 2-nerved; 2-keeled. Palea keels narrowly winged (the wings terminating in clavate appendages). Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Ovary apically glabrous. Stigmas 2.
Fruit, embryo and seedling. Hilum long-linear.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 58–72 microns long; 3.6–5.4 microns wide at the septum. Microhair total length/width at septum 11.7–17.1. Microhair apical cells 28–36 microns long. Microhair apical cell/total length ratio 0.48–0.52. Stomata common; 25–29 microns long. Subsidiaries dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common (in places); not paired; not silicified. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; mostly shortish dumb-bell shaped.
Transverse section of leaf blade, physiology. C4; XyMS. Mesophyll with radiate chlorenchyma; seemingly without circular cells (in the material seen). Midrib conspicuous, or not readily distinguishable; with one bundle only. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Sclerenchyma all associated with vascular bundles (rather depauperate).
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Arundinelleae. Soreng et al. (2015): Panicoideae; Tristachyideae. 1 species (G. indurata).
Distribution, phytogeography, ecology. East tropical Africa.
Mesophytic; species of open habitats. Clearings in thickets and woodland.
References, etc. Morphological/taxonomic: Phipps 1967. Leaf anatomical: studied by us.
Illustrations. • G. indurata: Clayton, Flora Zambesiaca 10 (1989)
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’.