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46 FIELDIANA: BOTANY, VOLUME 28
and the longer-beaked, larger, and more shining achenes which are
less prominently reticulate with cells broader than high, while from
R. Lechleri Steud. of Peru it differs in the broader leaves which are
not scabrid-serrulate on margins, and in various floral characters.
The distinguishing characteristics of R. ptaritepuiana are the
elongate, narrow leaves, clustered more at the base of the culm, and
not conspicuously scattered on the culm, the short brown panicles,
the shining achene marked with transversely broader than high superficial
cells, the elongate bilobed tubercle, and the 6 bristles which
equal or are longer than the achene.
Rhynchospora sanariapensis Steyermark, sp. nov.
Annua caespitosa; foliis setaceis, glabris, 2.5-5 cm. longis; culmis
filiformi-setaceis, glabris, 7-10 cm. altis; corymbis terminalibus,
glomerulis, 8-12 mm. altis, 5-12 mm. latis; floribus 6 vel pluribus;
spiculis lance olato-subulatis, 2-floris, 1-carpis, 3-3.5 mm. longis;
squamis 4, ovatis vel lanceolatis, acutis; stylo diviso; setis nullis;
achaenio oblongo-obovoideo, 0.9-1 mm. longo, 0.5 mm. lato, transversim
profunde 4-5-sulcato et prominente gibbo elevato, inter gibbo
subtilissime longitudinaliter stria to; tuberculo breve depresso,
0.05-0.1 mm. alto.
Corymbs with central cluster subsessile, the 2 lateral clusters
with 6 or more spikelets; bract shorter or longer than corymbs, 1-1.6
cm. long, scabridulous on margins; lower scales 0.5-1.5 mm. long, the
upper 2.25-3.5 mm. long; style divided into 2 slender branches;
achene somewhat narrowed below, rounded or subrruncate above,
tawny-brown, each face deeply 4-5 transversely sulcate with prominent
suba cutely angled ridges with fine striae running lengthwise
between the ridges, narrowly ridged lengthwise on each side
(Fig. 5, e, f).
Type in herb. Chi. Nat. Hist. Mus., collected in vicinity of Sanariapo,
near Rio Sanariapo, tributary of Orinoco river, Territorio
Federal Amazonas, alt. 100 m., September 8, 1944, Julian A. Steyermark
58469. Also collected among rock outcrops below mouth of Rio
Sanariapo, along Orinoco river, alt. 100 m., September 8, 1944,
Steyermark 58436.
Related to R. pluricarpa Gilg of the Matto Grosso-Parana' portion of
Brazil, but differs in its larger, oblong achene of different color,
prominent sulcations and ridges, and in the single fruit of the spikelets
instead of 4-5. From R. tenuis it is distinguished by the oblong,
instead of subglobose or turbinate, achene with more prominent sulcations,
narrower and less prominent tubercle, shorter spikelets,
and shorter culms, leaves, and bracts, while from R. lenella it is
separated by the shape of the achene, absence of the long scabrous
awn of the scales, and denser clusters of spikelets.
Rhynchospora sororopana Steyermark, sp. nov.
Perennis caespitosa; culmis tenuibus foliatis, 15-50 cm. altis,