Calyx of 5 distinct imbricated sepals. Corolla inflated-tubular, with the mouth a little open; upper lip broad and arched, keeled in the middle, notched at the apex; the lower woolly-bearded in the throat, 3-lobed at the apex, the middle lobe smallest. Stamens 4, with woolly filaments and very woolly heart-shaped anthers, and a fifth sterile filament smaller than the others. Seeds many, wing-margined.—Smooth perennials, with upright branching stems, opposite serrate leaves, and large white or purple flowers, which are nearly sessile in spikes or clusters, and closely imbricated with round-ovate concave bracts and bractlets. (Name from χελώνη, a tortoise, the corolla resembling in shape the head of a reptile.)
1. C. glàbra, L. A foot or two (or even 6–7°) high; leaves narrowly to rather broadly lanceolate (4–5´ long, 4–12´´ wide), gradually acuminate, serrate with sharp appressed teeth, narrowed at base usually into a very short petiole; bracts not ciliate; corolla white, or barely tinged with rose.—Wet places, Newf. to Minn., south to Fla. and Tex.
2. C. oblìqua, L. Less strict or with spreading branches, 1–2° high; leaves broadly lanceolate to oblong (2–5´ long), sometimes laciniately serrate, more veiny and duller, acute or obtuse at base, mostly short-petioled; bracts ciliolate; corolla deep and bright rose-color.—S. Ill. to Va. and Fla.
7. PENTSTÈMON, Mitchell. Beard-tongue.
Calyx 5-parted. Corolla tubular and more or less inflated, or bell-shaped, either decidedly or slightly 2-lipped; the upper lip 2-lobed, and the lower 3-cleft. Stamens 4, declined at the base, ascending above, and a fifth sterile filament usually as long as the others, either naked or bearded. Seeds numerous, wingless.—Perennials, branched from the base, simple above, with opposite leaves, the upper sessile and mostly clasping. Flowers mostly showy, thyrsoid or racemose-panicled. (Name from πέντε, five, and στήμων, stamen; the fifth stamen being present and conspicuous, although sterile.)
[*] Viscid or glandular above, more or less pubescent or glabrous below; leaves often toothed or denticulate.
[+] Thyrse somewhat open; leaves ovate-lanceolate to linear; corolla 9–12´´ long, the lower lip usually bearded within.
1. P. pubéscens, Solander. Stem 1–2° high, viscid-pubescent (at least the inflorescence); leaves oblong to lanceolate (2–4´ long), the lowest and radical ovate or oblong, usually denticulate; thyrse narrow; corolla dull violet or purple (or partly whitish), very moderately dilated, the throat nearly closed by a villous-bearded palate; sterile filament densely bearded.—Dry or rocky grounds, S. Maine (Miss Furbish) to Minn., south to Fla. and Tex.
2. P. lævigàtus, Solander. Stem 2–4° high, mostly glabrous except the inflorescence; leaves firmer, somewhat glossy, the cauline ovate- or oblong-lanceolate with subcordate clasping base (2–5´ long); thyrse broader; corolla white (commonly tinged with purple), abruptly and broadly inflated, the throat widely open; sterile filament thinly bearded above.—Moist or rich soil, Penn. to Fla. and westward, where the common form is
Var. Digitàlis, Gray. Stem sometimes 5° high; corolla larger and more abruptly inflated, white. (P. Digitalis, Nutt.)—Penn. to Iowa, Mo., Ark., etc.