This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Pentstemon Cobaea Nutt. Trans. Am. Phil. Soc. (II.) 5: 182. 1833-37.
Stem stout, densely and finely pubescent below, glandular-pubescent above, 1°- 2° high. Leaves oblong to ovate, firm, 3' - 5' long, dentate, the lower mostly glabrous and narrowed into margined petioles, the upper sessile or cordate-clasping, usually pubescent; thyrsus short, several-many-flowered, open; flowers about 2' long; calyx-segments lanceolate, acuminate, 5" - 7" long; corolla purple, puberulent without, glabrous within, its tube narrow up to the top of the calyx, then abruptly dilated and campanulate, the limb scarcely 2-lipped, the lobes short, rounded, spreading; sterile filament sparingly bearded; capsule ovoid, acute, pubescent, reticulate-veined, as long as the calyx.
Fig. 3766. P. Grandifiorus Nutt. In Fras. Cat. 1813
Glabrous and somewhat glaucous; stem stout, 2°-4° high. Leaves all entire and obtuse, the basal ones obovate, narrowed into broad petioles, those of the lower part of the stem sessile, oblong or oval, 1' - 2 1/2' long, the upper nearly orbicular, cordate-clasping, shorter; thyrsus open, leafy-bracted, the bracts orbicular, cordate; pedicels 2"-6" long; flowers nearly 2' long; calyx-segments lanceolate, acute, 3"-4" long; corolla lavender-blue, the tube rather abruptly dilated above the calyx, the limb somewhat 2-lipped; sterile filament incurved, villous and capitate at the summit; capsule acute, 8"-10" high, three times as long as the calyx.
On prairies, Illinois to Minnesota, North Dakota, Kansas and Colorado. Locally introduced eastward. June-Aug.
Pentstemon acuminatus Dougl.; Lindl. Bot. Reg. pl. 1285. 1829.
Glabrous and glaucous; stem rather stout, strict, 6'-2° high, leafy. Leaves firm, entire, the lower and basal ones oblong or spatulate, obtuse or acute, narrowed into petioles, the upper sessile or clasping, lanceolate or ovate-lanceolate, 2-3' long; thyrsus narrow, sometimes 1- sided, usually leafy-bracted below; pedicels becoming 4"-8" long in fruit; calyx-segments lanceolate, acute, 2"-3" long; corolla blue, 9" - 10" long, its tube rather gradually dilated, the limb 2-lipped; sterile filament bearded along the dilated summit; capsule acute, twice as long as the calyx.
In dry soil, Minnesota to Nebraska, Texas, Manitoba, Alberta, Oregon and New Mexico. St. Joseph's-wand. May-Aug.
Pentstemon glaber Pursh, Fl. Am. Sept. 738. 1814.
Glabrous, somewhat glaucous; stem ascending or erect, rather stout, leafy, 1°- 2° high. Leaves entire, firm, the basal and lower ones narrowed into petioles, the middle ones oblong or oblong-lanceolate, acuminate, sessile, the upper lanceolate, acuminate, sessile, scarcely clasping; thyrsus narrow, elongated, densely many-flowered; pedicels 3"-7" long in fruit; calyx-segments ovate-lanceolate, scarious-margined, abruptly acuminate 3" - 4" long, their margins commonly eroded; corolla blue or purple, 1' - 1 1/2' long, rather abruptly expanded above the calyx, the limb somewhat 2-lipped, the lobes rounded; sterile filament bearded at the slightly enlarged summit; capsule narrowly ovoid, acute, about twice as long as the calyx.
In moist soil, South Dakota to Nebraska, Wyoming and Arizona. Far western plants previously referred to this species prove to be distinct. May-Aug.