2. Penstemon cobaea Nutt. (cobaea beard-tongue, cobaea penstemon)

P. cobaea var. purpureus Pennell

Pl. 484 a–c; Map 2214

Stems 20–80 cm long, erect or ascending, sometimes from a spreading base, densely pubescent with mostly glandular hairs, the hairs slightly longer toward the stem tip, green, not glaucous. Basal leaves 3–24 cm long, the blade oblanceolate to spatulate, rounded to sharply pointed at the tip, tapered basally to a winged petiole, the margins entire to more commonly sharply toothed, the surfaces glabrous to more commonly glandular-hairy (rarely pubescent with nonglandular hairs), not glaucous. Stem leaves 3–15 cm long, the lowermost with the blade oblanceolate to narrowly oblong-elliptic, grading into lanceolate to ovate at the stem tip, sharply pointed at the tip, sessile or nearly so, the base of the lower blades tapered, grading through rounded to those of the uppermost leaves cordate and clasping, the margins sharply toothed, at least above the midpoint, the surfaces glabrous to more commonly glandular-hairy (rarely pubescent with nonglandular hairs), not glaucous. Inflorescences narrow panicles, the central axis glabrous or more commonly minutely glandular-hairy, green to yellowish green, not glaucous, with 3–6(–8) nodes, each with a pair of leaflike, ovate, clasping bracts, the branches ascending, with a pair of mostly branched clusters per node, each with 2–6 flowers. Calyces (8–)10–16 mm long at flowering, densely glandular-hairy, not glaucous, the lobes lanceolate to narrowly ovate. Corollas 35–55 mm long, the tube abruptly enlarged well below the midpoint, strongly bilabiate, the upper lip spreading to somewhat arched forward, the lower lip spreading to somewhat reflexed, either white or purple (then sometimes with a white ring at the base of the corolla lobes), rarely pink or light purple, the throat lined with darker reddish purple nectar guides and noticeably ridged on the lower side, minutely glandular-hairy externally and in the throat. Staminode white, strongly flattened toward the tip, bearded on the upper surface, the hairs shorter and yellow to light brown toward the base, curled-under apically and bearded with white or pale yellow hairs. Fruits 13–18 mm long. Seeds 2.5–3.5 mm long, black, the black ridges well-developed. 2n=16, 64. April–June.

Uncommon to scattered in the southern portion of the Ozark Division and disjunct in Bates County; introduced elsewhere in the state (Nebraska to Texas east to Iowa and Arkansas; introduced farther east and west). Limestone and dolomite glades and rock outcrops; also roadsides.

Missouri populations are on the eastern edge of the distribution of this Central United States endemic. Pennell (1935) and Steyermark (1963) treated plants from southwestern Missouri and adjacent Arkansas with purple corollas as a distinct variety, var. purpureus. Pennell stated that this variety was the showiest of all the beardtongues. Escapes from gardens involving purple-flowered plants have expanded the range of this morph. However, no additional characters have been shown to distinguish these from white-flowered plants and they are better treated merely as trivial color forms.