keys to the vascular plants of east texas - Botanical Research ...

566 CYPERACEAE/CYPERUS
Cyperus articulatus L., (jointed), CHINTÚL, JOINTED FLAT SEDGE. Perennial 0.5–1.4(–2) m tall, with
creeping rhizomes, forming colonies; culms with conspicuous septa; leaves few, basal, usually
reduced to small essentially bladeless sheaths; inflorescences essentially bractless or with very
small bracts, of rather loose digitate (–spicate) clusters of spikelets; spikelets 6–33(–55) mm
long (rarely surprisingly long); achenes 1.2–1.6 mm long. Moist grasslands, marshes, other wet
areas; widespread in s part of East TX, scattered to the n (e.g., Grayson (BRIT), Anderson, Hunt,
and McLennan (Turner et al. 2003) cos.; also Gulf Prairies and Marshes and South TX Plains; se
U.S. from SC s to FL w to TX. May–Oct. The rhizome has been used medicinally (Burkhill 1985),
and the sweet smelling roots have been used in perfumery (Judd et al. 1999). According to
Tucker et al. (2002), this species is the only North American Cyperus with a reed-like appearance
resembling larger plants of Juncus or Schoenoplectus.
Cyperus bipartitus Torr., (divided nearly to the base into two parts), SHINING FLAT SEDGE. Annual
to only 30 cm tall, very similar to C. flavescens and C. lanceolatus, distinguished by color of
scales and surface of achenes as in key; inflorescences with spikelets in loosely digitate heads or
glomerules; floral scales light to dark brown, usually with some reddish pigmentation; achenes
lenticular, 1–1.3(–1.5) mm long. Moist areas along rivers, lakes, seeps; Bowie Co. (Turner et al.
2003); Correll and Johnston (1970) and Turner et al. (2003) cited specimens of the closely related
C. niger Ruiz & Pavon from Austin and Washington cos—that species is known primarily
from the w U.S. (AZ, CA, NM, OK, w TX), and the two East TX localities are presumably C.
bipartitus; se Canada and widespread throughout much of the U.S. (Jul–)Aug–Oct(–Nov). [C.
rivularis Kunth] While not officially designated as such (e.g., TOES 1993; Carr 2002d; Poole et
al. 2002), given its limited distribution in the state, we consider this species to be of conservation
concern in TX. �
Cyperus compressus L., (flattened), POORLAND FLAT SEDGE. Small tufted annual (2–)6–15(–35) cm
tall; inflorescences with relatively few spikelets (usually 12 or less) in ± digitate clusters;
achenes 1–1.5 mm long, from ca. 3/4 to nearly as wide as long. Weedy and disturbed areas; Dallas,
Harris, Jefferson, Newton, Sabine, Wood (BRIT), Colorado, Harris, Nacogdoches, Polk, and
Tyler (Turner et al. 2003) cos.; also Gulf Prairies and Marshes; widespread in e 1/2 of the U.S. Jul–
Nov.
Cyperus croceus Vahl, (saffron-colored, yellow), BALDWIN’S FLAT SEDGE. Tufted perennial usually
15–45 cm tall; inflorescences of globose to ovoid, relatively crowded to dense clusters of spikelets,
the clusters 8–20 mm broad; spikelets 3–8 mm long; scales with green keel and reddish or
yellow-brown sides; achenes usually 1.3–1.8 mm long. Sandy open areas; widespread in East TX;
also n Gulf Prairies and Marshes and scattered to the w; e U.S. from PA s to FL w to MO and TX.
May–Oct. [ C. baldwinii Torr., C. globulosus of authors, not Aubl., C. globulosus var. robustus
(Boeck.) Shinners, C. retrorsus Chapm. var. robustus Kük.] The name C. globulosus has long been
mistakenly applied to this species (Tucker et al. 2002). A number of BRIT specimens have been
annotated by Stanley Jones (BRCH) as C. croceus � C. retroflexus or C. croceus � C. retrorsus.
Cyperus difformis L., (of unusual or differing forms), VARIABLE FLAT SEDGE, SMALL-FLOWER UM-
BRELLA SEDGE. Annual 10–30(–50) cm tall; roots red; leaves 2–4(–7) per culm, 1–4 mm wide; inflorescences
with spikelets digitately arranged in heads; heads globose or lobulate; spikelets 5
(–8) mm or less long; scales roundish, obtuse, very small, 0.5–0.8 mm long, green with brownish
or purplish sides; achenes 0.5–0.8 mm long. Unshaded shallow creek beds in perennially wet
mud over limestone or dolomite, also creek banks, lake shores, and other wet, often frequently
flooded areas; Travis (BRIT), Williamson (Carr 1988), and Newton (Bryson et al. 1996; Turner et
al. 2003) cos.; otherwise in TX known only from Harris Co. (Turner et al. 2003) near s margin of
East TX; first collected in TX in 1981 and first reported by Carr (1988); e. U.S. from NY s to FL w
to TX, also AZ, CA, ID, OR, and NM. Native of the Old World. Lipscomb (1980) discussed the
distribution of C. difformis in North America—the earliest known North American collection