Family-Graminae (Poaceae); Subfamily-Panicoideae; Tribe-Andropogoneae;
Generic Description: Ten species of the Old World tropics, common to flood plains and stream banks. Vetiveria is related to Sorghum subgen Parasorghum. Vetiveria pauciflora, with only 2-3 spikelet pairs per raceme, links it to Chrysopogon.
Tufted perennial; ligule a line of hairs. Inflorescence a panicle, its primary branches whorled, simple, each bearing a raceme; raceme typically long and slender, comprising (2-)3-10 spikelet pairs. Sessile spikelet laterally compressed, its callus obtuse to pungent, often large and conical; lower glume chartaceous to coriaceous, spinulose; upper glume shortly awned; upper lemma bidentate (Vetiveria pauciflora entire), with a slender or inconspicuous awn (Vetiveria zizanioides awnless). Pedicelled spikelet well developed.
The following generic description is transcribed from microfiche supplied with Watson, L. and M.J. Dallwitz. 1989. Grass Genera of the World, (with microfiche and data disks). Australian National University Printing Service, Canberra. Used with permission of the authors.
Generic synonymy. Mandelorna Steud., Lenormandia Steud.
Habit, vegetative morphology. Perennial (with aromatic roots); forming large clumps from stout rhizomes. Culms 50-300 cm high; herbaceous; unbranched above. Nodes glabrous. Culm internodes solid. The shoots not aromatic (but sometimes with aromatic roots). Leaves mostly basal; without auricles. Sheath margins free (the lower sheaths compressed). Leaf blades linear; without readily visible transverse veins; not disarticulating. Ligule a fringed membrane with a fringe of hairs.
Reproductive Organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant hermaphrodite and male or neuter); homomorphic; all in heterogamous combinations.
Inflorescence. Inflorescence of spike-like main branches, or paniculate (a panicle with slender, whorled, simple or rarely compound racemes); open, espatheate; not comprising 'partial inflorescences' and foliar organs. Spikelet-bearing axes 'racemes' (these with many spikelet pairs); with very slender rachides; disarticulating; disarticulating at the joints. 'Articles' linear; not appendaged; disarticulating transversely. Spikelets in pairs; secund (rarely), or not secund. With pedicellate spikelets. Spikelets consistently in 'long-and- short' combinations; in pedicellate/sessile combinations. Pedicels of the 'pedicellate' spikelets free of the rachis. The 'shorter' spikelets hermaphrodite. The 'longer' spikelets male-only, or sterile.
Female-sterile spikelets. Pedicelled, male spikelets similar to the sessile ones, or slightly smaller.
Female-fertile spikelets. Spikelets 4.5-10 mm long; compressed laterally; falling with the glumes (and with the joint and pedicel). Rachilla terminated by a female-fertile floret. Hairy callus present, or absent.
Glumes two; more or less equal; long relative to the adjacent lemmas; awned (G2, sometimes), or awnless; very dissimilar (lower rounded on back, upper naviculate). Lower glume convex on the back; not pitted; spinulose; 5 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. Proximal incomplete florets 1; epaleate; sterile. the proximal lemmas awnless; 2 nerved; similar in texture to the female-fertile lemmas (hyaline); not becoming indurated.
Female-fertile florets. 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; incised; not deeply cleft (bidentate); awnless, or mucronate, or awned. Awns when present 1. Awns from the sinus; geniculate; hairless (glabrous); much shorter than the body of the lemma, or about as long as the body of the lemma, or much longer than the body of the lemma. Lemmas hairless; non-carinate; 1-3 nerved. Palea present, or absent; when present very reduced; apically notched; awnless, without apical setae; not indurated (hyaline); nerveless. Lodicules present; 2. No third locidule. Lodicules free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small; not grooved; not noticeably compressed; smooth. Hilum short. Pericarp fused. Embryo large. Endosperm containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
First seedling leaf a well-developed lamina. The lamina broad; curved; 21-30 veined.
Abaxial leaf blade epidermis. Microhairs present; panicoid-type (but often balanoform--the thin walled apical cells quite broad and blunt); (39-)48-51(-54) microns long; 9-12.6 microns wide at the septum. Microhair total length/width at septum 3.8-5.5. Costal/intercostal zonation conspicuous. Intercostal zones of typical long-cells. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells more or less rectangular; having markedly sinuous walls (the sinuosities very tight in Vetiveria elongata). Papillae absent. Costal regions without 'pooid-type' silica-bodies; with 'panicoid-type' silica bodies (cross shaped, in Vetiveria zizanioides), or without 'panicoid-type' silica bodies; with tall-and-narrow silica bodies (exclusively of this type in Vetiveria elongata), or without tall- and-narrow silica bodies; without saddle-shaped silica bodies; without crescentic silica bodies; without oryzoid silica bodies; without sharp-pointed silica bodies; without round to oval silica bodies; without elongated, smooth silica bodies. Stomata common (predominating); 27-33 microns long; having guard-cells overlapped by the interstomatals (the interstomatal end walls very thickened in Vetiveria elongata); with triangular subsidiaries; without parallel-sided subsidiaries. Intercostal short-cells common; in cork/silica-cell pairs; silicified (the silica bodies tall and narrow). Costal short-cells predominantly paired.
Transverse section of leaf blade, physiology, culm anatomy. C4; XyMS-. PCR sheath outlines even. PCR cell chloroplasts with reduce grana; centrifugal/peripheral. Mesophyll with radiate chlorenchyma; not Isachne- type; without 'circular cells'; not traversed by colourless columns; without arm cells; without fusoids. Leaf blade adaxially flat. Midrib conspicuous; with a conventional arc of bundles; with colourless tissue adaxially (the adaxial mesophyll of the blade also extensively colourless in Vetiveria elongata, and with large intercellular cavities in Vetiveria zizanioides). No discrete, regular groups of adaxial bulliforms (except alongside the midrib). Without simple fans of bulliforms; without deeply-penetrating fans of bulliforms-plus-colourless cells; without narrow-penetrating groups of bulliforms-plus-colourless cells. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Exhibiting vascular bundles combining both adaxial and abaxial girders of sclerenchyma. Sclerenchyma all associated with vascular bundles.
Cytology Chromosome base number, x = 5 and 10. 2n = 20 and 40.
Taxonomy. Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae. 'Nearest neighbours' Sorghum, Sorghastrum, Chrysopogon, Bothriochloa.
Ecology, distribution. 10 species. Tropical Africa, Asia, Australia. Floodplains and streambanks.
Rusts and smuts. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae--Tilletia. Ustilaginaceae-- Ustilago.
Economic importance. Commercial essential oils; Vetiveria zizanioides (from the roots). Vetiveria zizanioides is valuable for hedging, and as a guard against soil erosion.