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

548 CYPERACEAE/CAREX
semi-open sandstone outcrops, and open pine barrens, or on thin soils over limestone, occasional
on Alfisols or even Histosols; throughout much of East TX sw to Caldwell and Gonzalez
cos.; also a few counties in the Cross Timbers and Prairies and Harris Co. in the n Gulf Prairies
and Marshes; se Canada and e U.S. w to WI, KS, and TX. Fruiting (late Mar–)late Apr–mid-
Aug(–early Sep).
Carex nigromarginata Schwein. var. floridana (Schwein.) Kük., (sp.: black-margined; var.: of
Florida), FLORIDA BLACK-MARGINED CARIC SEDGE. A facultative sciophyte in dry woods, frequently
dry sandy woods; widespread in the Pineywoods and the e edge and the n part of the
Post Oak Savannah, but absent from the Blackland Prairie and from the sw part of East TX; also
in the extreme ne part of the Gulf Prairies and Marshes; se U.S. from NC s to FL w to TX. Fruiting
late Feb–mid-Apr. [C. floridana Schwein.] Crins and Rettig (2002) treated this taxon as a distinct
species (C. floridana) and separated it from C. nigromarginata in the narrow sense (a species
of the e U.S. w to AR and MO), using the characters in the key below. The main difference is
apparently the rhizomes, a character they used to separate varieties of C. albicans. Varietal status
appears best suited to treat the variation seen in C. nigromarginata and is most consistent
with the treatment of other taxa in this section of Carex (e.g., C. albicans). The rank of variety is
thus being used here. The fruits are reportedly dispersed by ants, with a whitish swelling near
the base of the perigynium acting as an elaiosome (= appendage used in dispersal by ants or
other insects) (Gaddy 1986). Section Acrocystis
1. Rhizomes horizontally spreading to ascending, 17–75 mm long; stigmas 2 or 3; some achenes
biconvex or trigonous; culm bases usually weakly fibrous __________________________________ C. floridana
1. Rhizomes ascending to erect, 0–10 mm long; stigmas 3; achenes obtusely trigonous in cross
section; culm bases often strongly fibrous ________________________________________ C. nigromarginata
Carex oklahomensis Mack., (of Oklahoma), OKLAHOMA CARIC SEDGE. A facultative to obligate
heliophyte of open wet ditches, beaver ponds, and wet prairies, also sparingly in wet clearings of
forested areas; n part of East TX in Anderson, Camp, Freestone, Leon, Nacogdoches, Titus, and
Wood cos; sporadic in e U.S. from DE s to NC w to KS and TX. Fruiting Apr–May. Section Vulpinae
Carex oxylepis Torr. & Hook., (sharp-scaled), SHARP-SCALE CARIC SEDGE. A facultative sciophyte
that will tolerate some full sun, in rich low moist hardwood forests, frequently along floodplains
of forest creeks; throughout most of East TX except for the sw part; also in the Gulf Prairies
and Marshes from the Coastal Bend area northeastward; se U.S. from VA s to FL w to MO,
OK, and TX. Fruiting Mar–Apr(–early Jun). Section Hymenochlaenae
Carex ozarkana P. Rothr. & Reznicek, (of the Ozarks), OZARK CARIC SEDGE. A facultative
heliophyte in early successional wetlands on mineral soils, often in association with seepages,
seepy banks of streams, permanently wet ditches, pond shores, and wet depressions in
meadows and pastures, in sites usually dominated by Juncus spp., with loamy, usually acidic
soils, ranging from clay loams to silt loams; e part of the Red River drainage, the n parts of the
Post Oak Savannah and Pineywoods, and Sabine Co. further s; AR, LA, OK, and TX. Fruiting late
Apr–May. Section Ovales
Carex perdentata S.D. Jones, (having teeth), CONSPICUOUSLY-TOOTHED CARIC SEDGE, SANDSTONE
CARIC SEDGE. A plant of sun or shade conditions, primarily in sandy loam, on sandstone outcrops,
and granitic outcrops, or in thin soils over limestone, open mesic to submesic hardwood
forests, open hardwood-juniper forests, or woodlands in savannahs with granite outcrops; w
edge of East TX, mainly w edge of the Blackland Prairie and Colorado and Fayette cos. of the
Post Oak Savannah; also n part of the South TX Plains, Cross Timbers and Prairies, and Edwards
Plateau; OK and TX. Fruiting mid-Mar–early Jun. This species was described relatively
recently (Jones 1994b). Section Phaestoglochin