Protologue Description: AGROPYRON acadiense, sp. nov. Glaucissimum, stoloniferum; rhizomata squamigera pallide brunnea. Culmi solitarii vel pauci, glabri, 2-6.5 dm. alti, nodis (3) valde constrictis flexilibusque; innovationes duae vel plures, culmis molto breviores. Vaginae basilares plures, glabrae, nonnullae elaminatae; illae culmorum laeves glabraeque marginibus aliquondo breve ciliatis exceptis, inferiores purpureorosae internodia circum aequantes vel etiam ea (saltem apud innovationes) superantes, superiores internodiis breviores, ad oram laminae vaginis auriculatis angustiores. Ligulae circa 0.5 mm. longae, membranaceae erosaeque. Laminae e basi plus minus planato involutae, 5-16 cm. longae, basi ad 3 mm. latae, valde patentes rigidaeque, infra glabrae laevesque, supra in nervis scabrae marginibus praecipue basis versus barbulatis. Inflorescentia compacta e vagina superiore plus minus exerta; aliquando a folio subtendente superata, 4-8.5 cm. longa ad 1 cm. lata; rachi internodiis superioribus exceptis fere glabro. Spiculae 1.2-1.5 cm. longae, lateraliter compressae, paullum divergentes, 3-5 florae; glumae duas tertias spiculorum longitudine aequantes, glabrae, inferior 7-nervata, circa 8 mm. longa, carina apicem acutiusculum versus barbulata, superior 5-nervata, circa 9 mm. longa, carina apicem acutiusculum vel minute mucronulatum verses barbulata; lemmata glabra, 5-nervata, ad apicem in sublam ad 4 cm. longam dorso barbulatam abrupte contracta, circa 1-1.2 cm. longa; palae 2-carinatae carinis barbulatis, quam lemmata breviores, ad apicem minute ciliolate, truncatae paullum retusatae.
Very glaucous with a long, scaly, pale brown rootstock: culms solitary or few to a clump, 2-6.5 dm. tall, 3-noded, glabrous; nodes much contricted and flexible when fresh; innovation two to several much shorter than the culms; basal sheaths several, glabrous, some of them bladeless; those of the culms smooth and glabrous except the sometimes short-ciliate margins, the lower purplish-pink, about equalling or exceeding the internodes (those of the innovations longer than the internodes), the upper shorter than the internodes, all auriculate and contrcated to the blade at the throat: ligules about 0.5 mm. long, membranaceous and erose: blades involute from a flattened base, 5-16 cm. long, 3 mm. broad at base, strongly spreading and rigid, lower surface glabrous and smooth, upper surface scabrous on the nerves, margins barbulate especially toward the base: inflorescence compact, more or less exserted from the upper sheath, sometimes exceeded by the subtending leaf, 4-8.5 cm. long, up to 1 cm. broad, the rachis almost glabrous except the upper internodes which are slightly barbulate: spikelets 1.2-1.5 cm. long, laterally compressed, slightly divergent, 3-5 flowered; glumes about ? as long as the spikelets, inferior 7-nerved, about 8 mm. long, barbulate on the keel toward the acutish apex, superior 5-nerved, about 9 mm. long, barbulate on the keel toward the acutish or mintely mucronulate apex; lemmas glabrous, abruptly narrowed to a subulate tip which is up to 4 mm. long and barbulate dorsally, about 1-1.2 cm. long ; pales 2-keeled, with the keels barbulate, shorter than the lemmas, truncate and slightly notched at the minutely ciliolate apex.-NOVA SCOTIA: dry sandy beach of Bras d'Or Lake, Grand Narrows, Cape Breton, July 20, 1914, Fernald & St. John in Plantae Exsiccate Grayanae (TYPE in Gray Herb.), also Grand Narrows, July 27, 1898, John Macoun, Herb. Geol. Surv. Can. no. 21,030, distributed as A. occidentale.