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

CYPERUS/CYPERACEAE
577
around the spike axis, the spikes usually wider toward apex; spikelets with only 1(–2) scales;
achenes (2.4–)2.7–2.9(–3.2) mm long. Upland woods, bogs, sandy soils; widespread in East TX,
also n margin of Gulf Prairies and Marshes; e U.S. from NJ s to FL w to MO and TX. Jun–Sep.
Cyperus polystachyos Rottb., (many-spiked), MANY-SPIKE FLAT SEDGE. Tufted perennial; culms
usually 45 cm or less long; inflorescences variable, with 1–8(–12) main rays terminated by loose
to dense spike-like or head-like clusters of spikelets, or clusters sometimes sessile or sometimes
inflorescences secondarily branched; spikelets sessile to short-stalked, sometimes diverging �
at right angles from the axis, sometimes � strongly ascending; achenes lenticular, 0.8–1.2 mm
long, brownish to grayish, sometimes iridescent, sometimes with a grayish crusty appearance.
Stream banks, moist sand; widespread in Pineywoods and Post Oak Savannah; widely distributed
in e 1/3 of TX; e U.S. from ME s to FL w to OK and TX. Spring–fall. [C. polystachyos var.
leptostachyus Boeck., C. polystachyos var. texensis (Torr.) Fernald] We are following Jones et al.
(1997) in synonymizing var. texensis.
Cyperus pseudothyrsiflorus (Kük.) R. Carter & S.D. Jones, (mistaken for Cyperus thyrsiflorus).
Tufted perennial 40 cm or less tall; leaves usually with knot-like septa visible under a hand lens
owing to numerous cross veins between the main veins; inflorescences with spikelets in spikes,
the spikes loose enough that the inflorescence axis is easily visible when pressed and dried;
achenes 1.4–1.9 mm long. Disturbed areas, damp soils; Bexar, Cass, Gonzales, Liberty, Newton,
Rusk, and Travis (Turner et al. 2003) cos.; also Gulf Prairies and Marshes, Edwards Plateau, and
Trans-Pecos; in the U.S. known only from TX; also Mexico. Jul–Sep. [C. uniflorus Torr. & Hook. var.
pseudothyrsiflorus Kük.] Tucker (1994) synonymized this taxon with C. retroflexus. However, we
are following Carter and Jones (1997) and Tucker et al. (2002) in treating it as a distinct species.
Cyperus pseudovegetus Steud., (mistaken for Cyperus vegetus), MARSH FLAT SEDGE, SALTMARSH
FLAT SEDGE. Tufted perennial usually 50(–80) cm or less tall; inflorescences usually with 3–10
main rays terminated by head-like clusters of spikelets, sometimes secondarily branched;
spikelets small, 2.5–4 mm long; scales essentially linear, conspicuously sickle-shaped, 0.6–0.7
mm wide when spread out; achenes linear to linear-oblong, 1–1.5 mm long, maturing brownish.
Sandy soils; widespread throughout East TX w to Cross Timbers and Prairies; also Gulf Prairies
and Marshes and n part of South TX Plains; widespread in e 1/2 of the U.S. Jun–Oct. [C. virens
Michx. var. arenicola (Boeck.) Shinners]
Cyperus reflexus Vahl, (bent back), BENT-AWN FLAT SEDGE. Perennial with creeping rhizomes,
similar to C. acuminatus (which, however, has S-shaped spikelet scales) and C. pseudovegetus
(which has much narrower spikelet scales); inflorescences with spikelets in digitate, dense,
head-like clusters; inflorescence bracts 3–4, the longest erect or nearly so, appearing as a continuation
of the culm; scales of spikelets ca. 1.1 mm wide when spread out, often reddish with
greenish keels, straight at base but curved at tip; achenes pale brown, 0.9–1.2 mm long. Moist
sand; widespread in e 1/2 of TX; FL, LA, OK, and TX. Spring–summer. [C. arenicola Steud., C.
fraternus Kunth, C. reflexus var. fraternus (Kunth) Kuntze, C. pseudovegetus Steud. var. arenicola
(Steud.) Kük.]
Cyperus retroflexus Buckley, (reflexed), ONE-FLOWER FLAT SEDGE. Tufted perennial usually 3–35
(–80) cm tall; inflorescences with spikelets in dense to loose spikes; scales of spikelets at maturity
often deep red-brown with prominent green keel; achenes (1.8–)2–2.5 mm long. Sandy open
woods or prairies; nearly throughout TX; s U.S. from AL n to MO and w to NM. May–Oct. [C.
retroflexus var. pumilus (Britton) R. Carter & S.D. Jones, C. uniflorus Torr. & Hook. var. pumilus
Britton, C. uniflorus var. retroflexus (Buckley) Kük.] We are following a number of authorities
(e.g., Kartesz 1994, 1999; Tucker 1994; Tucker et al. 2002) in not recognizing infraspecific taxa in
this species. Given the extensive overlap in morphological characters between the varieties and
the lack of geographical isolation, treatment as a variable species without infraspecific taxa is