14.10 DACTYLIS L.
Kelly W. Allred

Plants perennial; cespitose, sometimes with short rhizomes. Culms to 2.1+ m, bases laterally compressed; internodes hollow; nodes glabrous. Leaves mostly basal, glabrous; sheaths closed for at least 1/2 their length; auricles absent; ligules membranous; blades flat to folded. Inflorescences panicles; primary branches 1-sided, naked proximally, with dense clusters of subsessile spikelets distally, at least some branches longer than 1 cm. Spikelets oval to elliptic in outline, laterally compressed, with 2–6 florets; rachillas glabrous, not prolonged beyond the distal floret; disarticulation above the glumes and beneath the florets. Glumes shorter than the florets, lanceolate, 1–3-veined, ciliate-keeled, awn-tipped; calluses short, blunt; lemmas 5-veined, scabrous to ciliate-keeled, tapering to a short awn; paleas 2-keeled, tightly clasped by the lemmas, unawned, apices notched; lodicules 2, glabrous, toothed; anthers 3; ovaries glabrous. Caryopses shorter than the lemmas, concealed at maturity, oblong to ellipsoid, falling free or adhering to the lemma and/or palea; hila round. x = 7. Name from the Greek daktylos, ‘finger’.

Dactylis is interpreted here as a variable monotypic genus, although five species are recognized by Russian taxonomists. Numerous infraspecific taxa have been recognized in Eurasia, where Dactylis is native, but it does not seem feasible to identify subspecies and varieties in North America.

SELECTED REFERENCE Stebbins, G.L., Jr. and D. Zohary. 1959. Cytogenetic and evolutionary studies in the genus Dactylis. Univ. Calif. Publ. Bot. 31:1–40.

1. Dactylis glomerata L.
Orchardgrass, Dactyle Pelotonné

Culms to 2.1+ m, erect. Leaves dark green; sheaths longer than the internodes, glabrous, usually keeled; ligules 3–11 mm, truncate to acuminate; blades (2)4–8(10) mm wide, elongate, lax, with a con-spicuous midrib and white, scabridulous to scabrous margins. Panicles 4–20 cm, typically pyramidal, lower branches spreading, upper branches appressed. Spikelets 5–8 mm, subsessile. Glumes 3–5 mm; lemmas 4–8 mm, scabridulous; paleas slightly shorter than the lemmas; anthers 2–3.5 mm. 2n = 14, 21, 27–31, 42.

Dactylis glomerata grows in pastures, meadows, fence rows, roadsides, and similar habitats throughout North America. Native to Eurasia and Africa, it has been introduced throughout most of the cool-temperate regions of the world as a forage grass. It provides nutritious forage that is relished by all livestock, as well as by deer, geese, and rabbits. When abundant, the pollen can be a major contributor to hay fever.

The species includes both diploid and tetraploid populations. Although several infraspecific taxa have been described, based generally on the size of the stomata and pollen, variation in pubescence, and panicle features, formal taxonomic recognition does not seem warranted. Numerous cultivars have been developed for agricultural use.