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General description:
Penstemon degeneri is a perennial herb from 25 to 40 cm tall with five or more, slender (1.0 to 2.5 mm diameter at base), leafy, short-pubescent stems and a suffrutescent caudex. The basal leaves are lanceolate, entire, and up to 6 cm long and 16 mm wide (Spackman et al. 1997). The cauline leaves are more linear, more pubescent, and more sessile. The unleafy, sparingly glandular inflorescence is 3 to 10 cm high, with 2 to 10 tubular flowers at the ends of the stems. The dark blue to violet corolla of the flower is gradually inflated, 14 to 19 mm long and 4 to 5 mm wide at the mouth. The corollas are slightly two-ridged on the floor and have straight, reddish guidelines and sparse yellow hairs in the corolla throat. The staminode is also bearded with sparse golden hairs for about half its length. The anther sacs are 2.0 mm across the connective and are longer than wide. The papery calyx is persistent and the dehisced capsules are 7 to 9 mm long, with small, dark brown, irregularly angled seeds (Beatty et al. 2004).
Look Alikes:
Penstemon degeneri is similar to P. radicosus in appearance, though P. radicosus is limited to Jackson County in northcentral, Colorado, and P. degeneri is found in southcentral Colorado. Penstemon griffinii is the only relative in the alliance in Colorado. It is characterized by having a deeply 2-ridged corolla and a dense covering of long, golden hairs on the floor and opening of the corolla and staminode. Penstemon degeneri has a less strongly ridged corolla and an opening with a few hairs and a glabrous floor. The staminode has an orange beard (Peterson and Harmon 1981). Penstemon griffinii has a basal rosette through the flowering period, and smaller, linear stem leaves (2-3 cm long, 2 mm wide), while Penstemon degeneri lacks a basal rosette at flowering time, and has longer and wider stem leaves (up to 6 cm long and 16 mm wide, Spackman et al. 1997). Penstemon griffinii has dense golden hairs in its corolla throat, while P. degeneri has sparser white to light yellow hairs. (Caution: both species have dense golden yellow hairs on the staminode which may be confused with hairs on the corolla itself).
Phenology:
Flowering occurs June through mid July, and fruits set late July (Spackman et al. 1997).