Grass Genera of the World

L. Watson and M. J. Dallwitz


Acostia Swallen

Named for M. Acosta-Solis, collector of the type specimen.

Sometimes referred to Digitaria or Panicum?

Habit, vegetative morphology. Slender perennial; densely caespitose. Culms 25–40 cm high; herbaceous. Culm nodes hairy to glabrous. Sheaths keeled above. Leaf blades narrow; 3–4 mm wide (7–13 cm long, narrowed to both ends); flat; without cross venation; persistent; a fringed membrane; very short.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence of spicate main branches; non-digitate. Primary inflorescence branches 3–4 (these appressed, rather distant, up to 4.5 cm long). Rachides neither flattened nor hollowed, not winged. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary and paired; secund; pedicellate (the pedicels shorter than the spikelets).

Female-fertile spikelets. Spikelets 2–2.5 mm long; abaxial; compressed dorsiventrally; biconvex; falling with the glumes; with conventional internode spacings. The upper floret not stipitate. Rachilla terminated by a female-fertile floret.

Glumes present; one per spikelet (or the lower vestigial); (the upper) long relative to the adjacent lemmas; densely hairy; pointed (beyond the fruit); awnless; non-carinate. Upper glume 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. The proximal lemmas awnless; more or less equalling the female-fertile lemmas to decidedly exceeding the female-fertile lemmas (as long as the spikelet); densely hairy.

Female-fertile florets 1. Lemmas decidedly firmer than the glumes; smooth; entire; awnless; hairless; glabrous; non-carinate; having the margins inrolled against the palea; with a clear germination flap (?). Palea present; awnless, without apical setae. Ovary glabrous (?). Stigmas 2 (?).

Fruit, embryo and seedling. Fruit small (1.7 mm long).

Taxonomy. Panicoideae; Panicodae; Paniceae.

Distribution, ecology, phytogeography. 1 species; Ecuador. Glycophytic (riverbanks).

Neotropical. Andean.

References, etc. Morphological/taxonomic: Swallen 1968.

Special comments. Fruit data wanting. Anatomical data wanting.


Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).

Index