Penstemon sect. Gentianoides

G. Don

Gen. Hist. 4: 640. 1837. (as Pentstemon)

Treatment appears in FNA Volume 17. Treatment on page 150. Mentioned on page 94, 246.

Herbs. Stems glabrous, glaucous, sometimes not. Leaves basal and cauline, sometimes basal few (P. subulatus), or essentially cauline (P. centranthifolius), opposite, leathery, rarely not (P. alamosensis, P. parryi), glabrous, rarely scabrous, glaucous, rarely not; basal and proximal cauline petiolate; cauline sessile or short-petiolate, blade ovate, oblanceolate, lanceolate, oblong, elliptic, linear, or linear-subulate, margins entire, rarely toothed. Thyrses ± interrupted, cylindric or ± secund, axis glabrous, rarely scabrous, cymes 2 per node, sometimes 1 per node (P. alamosensis); peduncles and pedicels spreading to ascending or erect. Flowers: calyx lobes: entire or erose, ± scarious, glabrous or sparsely glandular or glandular-pubescent; corolla red, scarlet, crimson, magenta, pink, orange, lavender, violet, reddish violet, or purple, bilaterally symmetric or nearly radially symmetric, bilabiate or weakly bilabiate, not personate, salverform, tubular-salverform, or tubular-funnelform, sometimes ventricose, glabrous or glandular-pubescent to glandular externally, glabrous or glandular-pubescent internally abaxially or wholly, throat slightly to gradually inflated, not constricted at orifice, rounded or slightly 2-ridged abaxially; stamens included or longer pair reaching orifice, filaments glabrous, pollen sacs opposite, dehiscing completely, explanate, sometimes navicular, connective splitting, sides glabrous, sutures smooth, sometimes papillate; staminode included, flattened distally or ± terete, 0.1–1(–2.5) mm diam., tip straight or recurved, glabrous or distal 10–40(–70)% papillate or hairy, papillae or hairs to 1.5 mm; style glabrous. Capsules glabrous. Seeds brown to black, angled, 1–4 mm.


w United States, n Mexico.


Species 11 (10 in the flora).

Section Gentianoides is not monophyletic. Molecular data (C. A. Wessinger et al. 2016) placed some of the species in a clade that includes sect. Coerulei and other species in a clade that includes sect. Spectabiles; still others may be allied with sect. Glabri (A. D. Wolfe et al. 2006). D. D. Keck (1937) included most of the species of sect. Gentianoides in subsect. Centranthifolii [an unpublished name] of sect. Peltanthera D. D. Keck, including Penstemon cerrosensis Kellogg, known only from Cedros Island off the west coast of Baja California, Mexico.

Selected References



1 Corollas glabrous externally. > 2
2 Corollas salverform, weakly bilabiate. > 3
3 Corollas 25–33 mm, tubes 8–10 mm; cauline leaf blades ovate to lanceolate. Penstemon centranthifolius
3 Corollas 18–26 mm, tubes 4–7 mm; cauline leaf blades lanceolate to linear or linear-subulate. Penstemon subulatus
2 Corollas tubular-funnelform, bilabiate. > 4
4 Corollas glabrous or glandular-pubescent internally; peduncles and pedicels ascending to erect. Penstemon confusus
4 Corollas glabrous internally; peduncles and pedicels spreading to ascending. Penstemon patens
1 Corollas glandular-pubescent externally. > 5
5 Corollas white-pilose and glandular-pubescent internally abaxially. Penstemon parryi
5 Corollas glandular-pubescent or glabrous internally abaxially. > 6
6 Calyx lobes sparsely glandular-pubescent. > 7
7 Staminodes glabrous. > 8
8 Staminodes 7–9 mm; leaves not leathery. Penstemon alamosensis
8 Staminodes 14–20 mm; leaves leathery. Penstemon havardii
7 Staminodes retrorsely hairy or sparsely to densely pilose distally. > 9
9 Corollas nearly radially symmetric, weakly bilabiate; staminodes: distal 2–3 mm retrorsely hairy, hairs yellow or whitish, to 1.5 mm. Penstemon superbus
9 Corollas bilaterally symmetric, bilabiate; staminodes: distal 2–7 mm sparsely to densely pilose, hairs yellow, to 1.2 mm. Penstemon wrightii
6 Calyx lobes glabrous. > 10
10 Staminodes: distal 2–3 mm retrorsely hairy, hairs yellow or whitish, to 1.5 mm; corollas nearly radially symmetric, weakly bilabiate. Penstemon superbus
10 Staminodes glabrous or distal 1–3 mm papillate, papillae golden yellow or reddish yellow, to 0.2 mm; corollas bilaterally symmetric, bilabiate. > 11
11 Corollas red to crimson, tubular-salverform, glandular-pubescent externally and internally; pollen sacs explanate. Penstemon utahensis
11 Corollas violet or reddish violet to purple or lavender, tubular-funnelform, glabrous or glandular-pubescent externally, glabrous or glandular-pubescent internally; pollen sacs navicular, sometimes explanate. > 12
12 Corollas glabrous or glandular-pubescent internally; pedicels ascending to erect. Penstemon confusus
12 Corollas glabrous internally; pedicels spreading to ascending. Penstemon patens