Eleocharis cancellata S.Watson

FLORA NOVO-GALICIANA
and the relationship between these two species deserves closer study. The speci-
mens collected by the Mexican Boundary Survey should be re-evaluated with
local material of E. acicularis var. occid.enta.lis.
C. WRIGHT, Coll. N. Me*. 1851 -52.
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Eleocharis cancellata S. Wats. Proc. Amer. Acad. 18:170.1883.
Not definitely known from Nueva Galicia, but to be sought in Los Altos de
Jalisco and adjacent Guanajuato and Zacatecas. The type was from San Luis
Potosí, hardly 100 km east of our limits (Morales, Schaffner 575, GH!, in part, the
lectotype). The species is hardly known except from near the city of San Luis
Potosí. It was reported from New Mexico by Svenson (1929), on the basis of
Wright 1937, but this was questioned by the same author in 1939, he having seen a
collection from Sonora made in 1851 by George Thurber, another member of the
Mexican Boundary Survey. Wright’s field lists for 1851 (Shaw, Elizabeth A. Charles
Wright on the Boundary, pp. [fl-viii, 1-44.1987) show that his no. 567, distributed
under the number 1937, was collected September 18 on “margins of pools in
mountain valleys descending to the San Pedro,” i.e., in pre-Gadsden Purchase
Sonora, now Santa Cruz County, Arizona. Thurber was in the same area earlier in
the summer. According to Kearney & Peebles (Arizona Flora 155. 1960), the
plant has not been re-collected in Arizona.
Very similar to Eleocharis acicularis but always dwarf as far as known, caes-
pitose, annual or of indefinite duration, the culms 1.5-4 cm high, radiating from a
delicate vertically branched rhizome; spikelets 2-4 mm long; scales tapering to a
subacute or blunt tip, in age often exposing the achenes; bristles wanting; anthers
0.2-0.3 mm long; style trifid; achenes broadly obovoid-pyriform, 0.6-0.7 mm long,
substipitate, white, shining, with 6 longitudinal ribs, ca 15-725 coarse and papil-
lose trabeculae in each series, and conspicuous translucent fenestration between
the trabeculae.
Plants that seem intermediate between this species and Eleocharis acicularis
(which see) have been collected in Aguascalientes and northwestern Guanajuato,
NEW YORK BOTANICAL GARDEN
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