1. Gutierrezia texana (DC.) Torr. & A. Gray
Pl. 235 i–k; Map
985
Plants annual,
with taproots. Stems solitary, 10–100 cm long, erect or strongly ascending,
with numerous ascending to loosely ascending branches from below the midpoint,
longitudinally lined or ridged, glabrous. Basal leaves absent. Stem leaves
sessile or less commonly short-petiolate, 0.5–5.0 cm long, the blade narrowly
linear to linear-lanceolate or linear-oblanceolate, mostly sharply pointed at
the tip, more or less tapered to the nonclasping base, the margins entire, the
surfaces glabrous but with moderate to dense, impressed resinous dots, often
somewhat sticky to the touch. Inflorescences appearing as more or less
flat-topped panicles, the heads solitary or in small, loose clusters along the
branches and/or at the branch tips, the branch tips and stalks short to
relatively long, with few leaflike, linear bracts 0.3–1.0 cm long. Heads
radiate, sticky, resinous. Involucre 2–4 mm long, narrowly cup-shaped to
obconical. Involucral bracts in 2–4 unequal, overlapping series,
oblong-lanceolate to oblong-ovate, with a straw-colored to yellowish, hard,
shiny basal portion (this sometimes with a slender, green midvein) and an
ascending, triangular or diamond-shaped, green tip, glabrous but the green
portion finely resin-dotted. Receptacle flat or slightly convex, minutely hairy
around the attachment points of the florets. Ray florets 5–14, pistillate, the
corolla 3–6 mm long, yellow, sometimes persistent at fruiting. Disc florets 7–13,
perfect, the corolla 1.5–2.5 mm long, yellow. Pappus of the ray and disc
florets similar, a minute, light-colored crown or ridge less than 0.2 mm long,
rarely a minute, toothed (appearing scalelike) ring, always much shorter than
the corolla. Fruits 0.8–1.5 mm long, oblong-obovoid, sometimes slightly
flattened, with 6–9 fine, green nerves, the surface otherwise densely pubescent
with short, grayish purple hairs, purplish brown to nearly black. 2n=8,
10, 16. (July–)October.
Introduced,
known only from a single collection from the city of St. Louis (Oklahoma to
Texas and adjacent Arkansas and Louisiana; Mexico; introduced in Illinois and
Missouri). Railroads.
This species was
reported by Steyermark (1963) in the addendum at the end of his Flora of
Missouri, based on a specimen collected by Viktor Mühlenbach in the St.
Louis railyards. A second variety (var. glutinosa (S. Schauer) M.A.
Lane), with heads having more florets and a better-developed pappus, occurs in
eastern Mexico and southern Texas.