5. Penstemon pallidus Small (pale beard-tongue)

Pl. 485 a–c; Map 2217

Stems 25–60 cm long, erect or ascending, densely pubescent with minute, nonglandular hairs, also with moderate to dense, longer, glandular hairs, green to grayish green, not glaucous. Basal leaves 2–12(–18) cm long, the blade oblanceolate to spatulate, obovate or elliptic, rounded to bluntly pointed at the tip, tapered basally to a usually winged petiole, the margins entire or nearly so to bluntly or sharply and sometimes minutely toothed, the surfaces moderately to densely pubescent with shorter nonglandular and longer glandular hairs, sometimes mostly along the margins and main veins, not glaucous. Stem leaves 2–10 cm long, the lowermost with the blade oblanceolate to narrowly oblong-elliptic or narrowly ovate, grading into lanceolate or narrowly lanceolate at the stem tip, bluntly to 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 usually shallowly cordate and clasping, the margins entire or nearly so to bluntly or sharply and sometimes minutely toothed, at least above the midpoint, the surfaces pubescent with shorter nonglandular and longer glandular hairs, sometimes mostly along the margins and main veins, not glaucous. Inflorescences narrow to occasionally more broadly pyramidal panicles, the central axis densely glandular-hairy, green to grayish green, not glaucous, with 3–8 nodes, each with a pair of relatively small, linear to narrowly lanceolate, somewhat clasping bracts, the branches loosely to strongly ascending or arched upward, with a pair of few-to several-branched clusters per node, each main branch with 2–9(–16) flowers. Calyces 3–5 mm long at flowering, densely glandular-hairy, not glaucous, the lobes ovate. Corollas 17–23 mm long, the tube abruptly but relatively slightly enlarged at about the midpoint (usually very slightly so on the lower side), strongly bilabiate, the upper lip spreading to somewhat recurved, the lower lip slightly spreading to nearly straight, white or occasionally pale pinkish- to purplish-tinged, the throat appearing slightly flattened, relatively strongly 2-ridged and usually lined with purple nectar guides on the lower side, minutely glandular-hairy externally and sparsely to moderately nonglandular-hairy in the throat. Staminode white, strongly flattened toward the tip, white-hairy on the upper surface, slightly curved downward apically and bearded with yellow hairs. Fruits 5–7 mm long. Seeds 0.5–0.8 mm long, brown to dark brown, the tan to reddish brown ridges usually poorly developed. 2n=16. April–July.

Scattered to common nearly throughout the state, but absent or uncommon in the southern portion of the Mississippi Lowlands Division and the western half of the Glaciated Plains (eastern U.S. west to Minnesota, Kansas, and Arkansas; Canada). Glades, ledges and tops of bluffs, upland prairies, savannas, and openings of dry upland forests; also pastures, old fields, quarries, railroads, and roadsides; on both acidic and calcareous substrates.

This species is morphologically similar to P. arkansanus. For further discussion, see the treatment of that species. Steyermark (1963) noted that this species usually appears hairier than other members of the genus in Missouri. Pennell (1935) hypothesized that the colonization of P. pallidus into much of the easternmost states occurred relatively recently.