8 B Canadian Arctic Expedition, 1913-18 



The species A. gracilis nob. from north of Lake Superior, collected by Dr. 

 R. Bell; A. brizoides nob. from St. Paul island, Bering sea, by James M. Macoun, 

 and A. chrysantha nob. from sixteen miles west of Nome city, Alaska, by J. B. 

 Flett. Furthermore A. trichopoda nob. from Mansfield island and Nottingham 

 island, Hudson bay, collected by Dr. R. Bell, and of which the diagnosis ^ reads 

 as follows : 



"Stolonif erous : culms weak, about twenty cm. in height, enclosed by the 

 leaf-sheaths: leaf -blades broad, flat and glabrous, longer than the internodes: 

 inflorescence a lax-flowered panicle with the glabrous, capillary branches in 

 twos and threes: spikelet three-flowered, one or two on each branch: empty 

 glumes unequal, quite broad, acuminate, membranaceous, three-nerved: flower- 

 ing glume broad, pointed and often awned, at least in the basal flower, hairy at 

 the base: palet bidentate, shorter than the flowering glume. A near ally of A, 

 mucronata Hack." 



Finally may be mentioned that John Murdoch collected an Arctophila near 

 Point Barrow which Hackel has described as A. mucronata, fide Beal: Grasses 

 of North America.^ The diagnosis reads as follows: 



"A smooth, stout grass, 15-25 cm. high. Leaves 6-8 in number crowded; 

 ligule broad, lacerate, 2 mm. long; blades flat, abruptly pointed, 5-12 cm. long, 

 6 m.m. wide. Panicle shining, yellowish, open, partially included, narrow or 

 pyramidal, 5-7 mm. long, rays in twos or fours, refiexed, the longest 3-7 cm. 

 long, bearing 2-3 spikelets near the apex. Spikelets 2-flowered, joint of rachilla 

 0,6 m.m. long, smooth or very sparingly hairy; empty glumes subequal, 3-3, 

 3 m.m. long, soft, thin, first ovate, 1-nerved, second broader, 3-nerved; floral 

 glume broadly oval, 3,5 m.m. long, 3 mm. wide, 5-nerved, margin scarious, 

 apex irregularly toothed or torn, the central nerve extending to the tip or into a 

 short mucro; palea broad; 1,5 mm. long." 



It is thus characteristic of A. trichopoda and A. mucronata that the midrib 

 of the flowering glume is extended into an arista in the former, and in a mucro 

 in the latter, wMle in all the other species the midrib does not extend beyond 

 the apex of the glume, a structure which certainly would be anomalous in the 

 genus Colpodium Trin. (as understood by Bentham), because there the midrib 

 never reaches the top of the glume. 



These species of ArctophUa may naturally be classified in two sections : 



I. Macrostachyae. 



Spikelets, when fully developed, five- to seven-flowered, the base acute during 



anthesis. 

 A. fulva, A. remotiflora, and A. pendulina. 



II. Brachystachyae. 



Spikelets two- to four-flowered, the base obtuse during anthesis. 



A. brizoides, A. chrysantha, A. deflexa, A. gracilis, A. latiflora, A. mucronata, 



A. poecilantha, A. scleroclada, A. similis, and A. trichopoda. 



Dupontia R. Br. 



The genus was established by Robert Brown ' and characterized as foUows: 

 "Gluma subaequivalvis, scariosa, concava, mutica, locustam 2-3-floram sub- 

 aequans. Perianthia mutica, scariosa, (basi barbata), altero pedicellato; valvulis 

 integris, inferiore concava. Lodiculae 2. Ovarium imberbe. Stigmata sub- 



sessilia. Caryopsis . Gramen glabrum erectum. Folia linearia, plana, 



vaginis semifissis, basi Integra. Panicula simplex, coarctata, fusco et purpur- 

 ascenti varia, pedicellis cumlocustis continuis, perianthiis separatim solubilibus." 

 The genus was named in honor of Monsieur Dupont of Paris, author of a 

 valuable essay on the sheath of the leaves of grasses, and of observations on the 

 genus Atriplex. 



' Fedde's Repert. I.e. 



» Vol. 2, New York, 1896, p. 556. 



•Chloris Melvilliana I.e., p. 228. 



