The grass genera of the world
Habit, vegetative morphology. Pilose annual; culms geniculate or prostrate at base, rooting at the nodes. Culms 15–80 cm high; herbaceous; branched above. Culm nodes hairy. Culm internodes hollow. Leaves not basally aggregated; non-auriculate; without auricular setae (but with auricular hairs). Leaf blades linear-lanceolate to lanceolate; broad, or narrow; 5–15 mm wide (5–12 cm long); flat, or rolled; exhibiting multicellular glands abaxially (at the bases of the microhairs). The abaxial leaf blade glands intercostal. Leaf blades without cross venation; persistent. Ligule a fringe of hairs; truncate; 0.5–1.5 mm long. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open to contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; shortly pedicellate, or subsessile; imbricate.
Female-fertile spikelets. Spikelets 5–8 mm long; not noticeably compressed (subglobose); disarticulating between the glumes (the upper glume falling with the spikelet); not disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension with incomplete florets. Hairy callus absent. Callus absent.
Glumes two; more or less equal; about equalling the spikelets; long relative to the adjacent lemmas; hairy (villous and glandular); without conspicuous tufts or rows of hairs; pointed (subacute); awnless; non-carinate (broadly rounded abaxially); similar. Lower glume about equalling the lowest lemma; 9 nerved, or 11 nerved. Upper glume 9 nerved, or 11 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awnless (or with only minute vestiges of awns).
Female-fertile florets 3–6. Lemmas with an incurved, emarginate apex and a narrow awned lobe at each margin, and sometimes with 1–2 shorter, additional lobes; becoming indurated; incised (between excurrent nerves); 3–8 lobed; not deeply cleft; awned. Awns 2, or 3, or 5; median and lateral (sometimes), or lateral only (the two marginal nerves excurrent into large awns, the median and other nerves occasionally contributing smaller awns); the median (when present) similar in form to the laterals; apical; non-geniculate; hairy (and glandular); when present, much shorter than the body of the lemma to about as long as the body of the lemma; entered by one vein. The lateral awns exceeding the median. Lemmas hairy (the lower two profusely so between the nerves, the upper ones hairy only at the margins); non-carinate (abaxially rounded to flattened); without a germination flap; 9 nerved; with the nerves non-confluent. Palea present; relatively long (but narrower than the lemma); minutely apically notched; thinner than the lemma; not indurated (thinly leathery); 2-nerved; 2-keeled. Palea keels hairy. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers 3–4 mm long (yellow). Ovary apically glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit compressed dorsiventrally (ventrally flattened). Hilum short. Pericarp fused. Embryo large; with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae seemingly absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; Enneapogon-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhair basal cells 210–480 microns long. Microhair total length/width at septum 30. Microhair apical cell/total length ratio 0.01. Stomata common. Subsidiaries dome-shaped and triangular. Intercostal short-cells seemingly absent or very rare; not paired. Intercostal silica bodies absent. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; predominantly panicoid-type; mostly dumb-bell shaped.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheath outlines uneven. PCR sheaths of the primary vascular bundles complete. PCR sheath extensions absent. PCR cell chloroplasts centrifugal/peripheral. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells (perhaps, in places), or not traversed by colourless columns. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (between adjacent bundles, and each group corresponding with an abaxial bulliform group); in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans (some of the simple fans of the deeply-penetrating type, some of the others seeming to link with traversing colourless columns). Many of the smallest vascular bundles unaccompanied by sclerenchyma, or all the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Special diagnostic feature. Female-fertile lemmas with an incurved-emarginate apex, and a narrow awned lobe at each margin (sometimes with 12 shorter, additional lobes).
Classification. Watson & Dallwitz (1994): Chloridoideae; Pappophoreae. Soreng et al. (2015): Chloridoideae; Eragrostideae; Cotteinae. 1 species (K. nigrirostris).
Distribution, phytogeography, ecology. Southern Africa.
Xerophytic; species of open habitats; glycophytic. In semi-desert.
References, etc. Morphological/taxonomic: de Winter 1961. Leaf anatomical: photos provided by R.P. Ellis.
Illustrations. • General aspect (K. nigrirostris): Gibbs Russell et al., 1990
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’.