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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Tarigidia Stent

Habit, vegetative morphology. Glaucous perennial; caespitose. Culms 80–150 cm high; herbaceous; branched above, or unbranched above. Culm nodes glabrous. Culm internodes solid. Plants unarmed. Young shoots intravaginal. Leaves mostly basal (but cauline leaves conspicuous); slightly auriculate, or non-auriculate. The sheath bases sometimes profusely hairy. Leaf blades linear; narrow; 3–6 mm wide; flat (with thickened margins); without cross venation; persistent. Ligule an unfringed membrane; truncate; 1–5 mm long. Contra-ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile (in that some at the raceme bases may be sterile).

Inflorescence. Inflorescence a false spike, with spikelets on contracted axes, or paniculate; contracted; spicate (or the lower branches ascending). Inflorescence with axes ending in spikelets, or axes not ending in spikelets (rarely, the lower branches are shortly produced). Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ‘racemes’ (at the base of the inflorescence), or capitate (at the apex); disarticulating (at least the lower branches do so); falling entire. Spikelets clustered or in pairs on lower panicle branches; secund; shortly pedicellate; imbricate.

Female-fertile spikelets. Spikelets 4–4.5 mm long; abaxial; compressed dorsiventrally; falling with the glumes; not disarticulating between the florets; with conventional internode spacings. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus absent.

Glumes two; very unequal (the lower sometimes much reduced), or more or less equal (usually); shorter than the spikelets; shorter than the adjacent lemmas; free; hairy (sometimes densely so); pointed (acuminate); awnless; non-carinate. Lower glume shorter than the lowest lemma; 1 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; epaleate; sterile. The proximal lemmas awnless; 5–7 nerved; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas (papery, with long spreading hairs between nerves and at the margins); not becoming indurated.

Female-fertile florets 1. Lemmas elliptical-obtuse; similar in texture to the glumes; not becoming indurated; entire; pointed; awnless; hairless; non-carinate; having the margins lying flat on the palea; without a germination flap. Palea present; relatively long; tightly clasped by the lemma; entire; awnless, without apical setae; textured like the lemma; not indurated; 2-nerved. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers 2.5 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; red pigmented.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells having markedly sinuous walls and having straight or only gently undulating walls (i.e., mixed). Microhairs present; panicoid-type; (69–)78–93(–99) microns long; 4.5–5.1 microns wide at the septum. Microhair total length/width at septum 13.5–20.7. Microhair apical cells (37.5–)42–50(–51) microns long. Microhair apical cell/total length ratio 0.5–0.56. Stomata common; 30–33 microns long. Subsidiaries high dome-shaped (mostly), or triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; cross shaped to butterfly shaped; not sharp-pointed.

Transverse section of leaf blade, physiology. C4; XyMS–. PCR cell chloroplasts centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles (one large bundle, about 10 small); with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Anthephorinae. 1 species (T. aequiglumis).

Distribution, phytogeography, ecology. Southern Africa.

Mesophytic to xerophytic; species of open habitats; glycophytic. Dry grassland.

Hybrids. A taxon sharing features of Digitaria and Anthephora: originally suggested as an intergeneric hybrid - which accords with absence of fruit in material seen, and the scattered distribution.

References, etc. Morphological/taxonomic: Stent 1932; Loxton 1974. Leaf anatomical: this project.

Special comments. Fruit data wanting. Illustrations. • General aspect, spikelet cluster (T. aequiglumis): Gibbs Russell et al., 1990


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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’.

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