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The grass genera of the world

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

Rugoloa Zuloaga

~ Panicum pilosum

Type species: R. pilosa (Sw.) Zuloaga.

Habit, vegetative morphology. Perennial; rhizomatous (culms rooting and branching at the lower nodes, then erect). The flowering culms leafy. Culms to about 100 cm high; herbaceous. Leaves not basally aggregated. Leaf blades lanceolate to ovate-lanceolate; about 6–14 mm wide; tending to cordate, or not cordate, not sagittate; not pseudopetiolate.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality; hermaphrodite.

Inflorescence. Inflorescence paniculate; open; more or less irregular; non-digitate; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes paniculate. Spikelets paired; secund (the branches one-sided); shortly pedicellate. Pedicel apices cupuliform.

Female-fertile spikelets. Spikelets 1–1.5 mm long; narrowly elliptic; compressed laterally to not noticeably compressed; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; very unequal; (the upper) about equalling the spikelets; long relative to the adjacent lemmas; lateral to the rachis; hairy, or hairless; pointed; awnless; similar in form, but the lower much smaller. Lower glume about 0.5 times the length of the upper glume; shorter than the lowest lemma; 3 nerved. Upper glume not saccate; 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, or epaleate. Palea of the proximal incomplete florets fully developed, or reduced. The proximal incomplete florets male, or sterile. The proximal lemmas awnless; 5 nerved; more or less equalling the female-fertile lemmas.

Female-fertile florets 1. Lemmas ellipsoid; decidedly firmer than the glumes; becoming indurated; entire; pointed; awnless; hairless (?); non-carinate; having the margins inrolled against the palea. Palea present; relatively long; tightly clasped by the lemma.

Fruit, embryo and seedling. Fruit ellipsoid. Hilum short. Embryo large; waisted.

Transverse section of leaf blade, physiology. C3.

Classification. Watson & Dallwitz (1994): not described separately. Soreng et al. (2015): Panicoideae; Panicodae; Paspaleae; Otachyriinae. 3 species (R. hylaeica, R. pilosa, R. polygonata).

Distribution, phytogeography, ecology. Brazil, Jamaica.

Not known in Australasia.

References, etc. Morphological/taxonomic: Acosta, J.M., Scataglini, M.A., Reinheimer, R. and Zuloaga, F.O. (2014). A phylogenetic study of subtribe Otachyriinae (Poaceae, Panicoideae, Paspaleae). Plant Syst. Evol. 300:2155–2166.

Special comments. Currently encoded entirely from the inadequate original description. Fruit data wanting. Anatomical data wanting. Illustrations. • R. pilosa, as Panicum pilosum: Trinius, Species Graminum 2 (1829)


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’.

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