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

XYRIS/XYRIDACEAE 1141
11. Plant bases greenish, pale to dark brown, or straw-colored.
14. The two primary scape ridges (1 spike length below a spike) commonly flattened,
in combination nearly as broad as or broader than the body of the scape
(on living plants), often scabrous; leaves commonly spreading, the upper, nonclasping
portion elliptic-linear; mature spikes ovoid to subglobose, blunt or acute,
the bracts usually tightly imbricated; plants perennial (except in drought), often
in shaded situations _____________________________________ X. difformis var. difformis
14. The two primary scape ridges not as above, hardly distinguishable from the
somewhat flattened scape and certainly not, in combination, as broad as the
body of the upper scape, not scabrous; leaves commonly ascending-linear;
mature spikes narrowly ovoid to oblong, blunt, the bracts rather loosely imbricated;
plants often annual (except in moistest, warmest situations), primarily of
sunny disturbed situations or of sandy open swamps (this is the most abundant
Xyris of roadside ditches and it frequently invades disturbed or fallow,
open wetlands) _______________________________________________________ X. jupicai
Xyris ambigua Beyr. ex Kunth, (ambiguous), YELLOW-EYED-GRASS, COASTAL-PLAIN YELLOW-EYED-
GRASS. Perennial, solitary or in small tufts; leaves 10–40 cm long, 3–20 mm wide, in broad fans;
base of inner leaves with very prominent dark longitudinal veins in sharp contrast to the white
or pale intervening tissue (older leaves need to be removed to observe this); scapes (15–)70–100
cm long; spikes 10–30 mm long. Moist sandy areas, sandy peats, bog margins, ditches, lake
shores, savannahs, and pine flatwoods, not found where its base would be submersed for any
length of time; s parts of the Pineywoods and Post Oak Savannah w to near e margin of the
Blackland Prairie; also n part of the Gulf Prairies and Marshes; se U.S. from VA s to FL w to AR
and TX. Flowers opening in the early morning, usually closed by midday; May–Jul. Kral
(2000a) noted that this species “is one of the more widespread and weedy of xyrids, frequently
invading disturbed moist, sandy areas. It is also one of the most variable in habit and apparently
forms intermediates with X. stricta …” See further discussion under X. stricta. m/306
Xyris baldwiniana Schult., (for its discoverer, William Baldwin, 1779–1819, botanist and physician
of PA), BALDWIN’S YELLOW-EYED-GRASS. Perennial growing in large tufts; leaves 10–30 cm
long, usually 0.5–1 mm wide; scapes 20–40(–50) cm long; spikes 4–7 mm long. Moist sandy areas,
sandy peats, hillside bogs, ditches, and savannahs; Pineywoods and Post Oak Savannah w to
near e margin of the Blackland Prairie; se U.S. from NC s to FL w to AR and TX. Flowers opening
in the morning; flowering early in the season–Jul. This is the only U.S. Xyris species with
beardless staminodia (Kral 1966a).
Xyris caroliniana Walter, (of Carolina), CAROLINA YELLOW-EYED-GRASS. Perennial, solitary or in
small tufts; leaves 20–50 cm long, 2–5 mm wide; scapes 50–110 cm long; spikes (13–)15–30 mm
long; sepal keels fimbriate. Moist to well-drained sands of pine or oak-pine areas, never in permanently
wet soils; Angelina, Jasper (VDB), Hardin, Newton, and Tyler (Turner et al. 2003) cos.
in the se portion of the Pineywoods; e U.S. from NJ s to FL w to TX. Flowers usually opening in
the afternoon; Jun–Aug. [X. arenicola Small, X. flexuosa Muhl. ex Elliott] Xyris caroliniana has
been confused with X. torta but can be distinguished as follows (Kral 1966a): Xyris caroliniana
—deepset, very broad and chestnut brown leaf bases; narrower usually longer spikes; exserted,
almost linear lateral sepals; bracts lacking an apical tuft of hairs; seeds narrow, 0.8–1 mm long;
flowers usually opening in the afternoon; Xyris torta—smaller, more shallowly set, reddish or
pink leaf bases; shorter broader spikes; included curvate lateral sepals; bracts with an apical
tuft of short hairs; seeds plump, ca. 0.5 mm long; flowers opening in the morning.
Xyris difformis Chapm., (of two forms), BOG YELLOW-EYED-GRASS. The following two varieties
(not distinguished on the county distribution map) occur in East TX: