1	"Herbage hairy"	2
1	"Herbage (proximal to inflorescence) glabrous"	14
2	"Herbage glandular-hairy; corolla lobes glandular-hairy inside"	3
2	"Herbage nonglandular-hairy (distal stem, inflorescence occasionally also glandular); corolla lobes glabrous inside or corolla floor nonglandular-hairy"	6
3	"Herbage densely glandular-hairy; flower stem erect, generally 4--7 dm, stout"	"Penstemon sudans"
3	"Herbage sparsely glandular-hairy; flower stem generally decumbent at base, generally < 4 dm"	4
4	"Corolla 12--18 mm, upper lip white; leaves 8--18 mm wide"	"Penstemon deustus var. deustus"
4	"Corolla 9--15 mm, upper lip +- brown; leaves 3--28 mm wide"	5
5	"Leaves lanceolate, 2.5--8(14) mm wide; calyx 2.5--5 mm, lobes lanceolate, acute; corolla 10--12(15) mm"	"Penstemon deustus var. pedicellatus"
5	"Leaves ovate to +- round, 7--28 mm wide; calyx 3.5--6.5 mm, lobes narrowly lanceolate, sharply acute or long-tapered; corolla 9--11 mm"	"Penstemon deustus var. suffrutescens"
6	"Inflorescence glabrous; calyx 1--4.5 mm; corolla 6--10 mm"	7
6	"Inflorescence hairy, generally glandular; calyx 3--13 mm; corolla 10--30 mm"	8
7	"Leaves generally all cauline, +- linear, folded lengthwise, arching-recurved"	"Penstemon cinicola"
7	"Leaves best developed on basal sterile stems, these (ob)lanceolate to obovate, cauline leaves ascending (folded lengthwise), not arching-recurved (see 29 for vars.)"	"Penstemon procerus"
8	"Calyx 3--8.5 mm"	9
8	"Calyx (4.5)6--13 mm"	11
9	"Basal leaves (15)20--75 mm, (2)4--32 mm wide, petioled, cauline leaves sessile"	"Penstemon humilis var. humilis"
9	"Leaves similar throughout, 5--20 mm, 0.8--6 mm wide, petioled"	10
10	"Plant spreading to ascending, not mat-forming; stem 1--3 dm; calyx lobes ovate"	"Penstemon californicus"
10	"Plant low, generally mat-forming; stem 0.5--1.5 dm; calyx lobes lanceolate"	"Penstemon thompsoniae"
11	"Corolla gradually expanded into throat, throat 4--6 mm wide when pressed; staminode +- included, not coiled at tip"	12
11	"Corolla abruptly and widely expanded into throat, throat 7--12 mm wide (4--5 mm in <i>Penstemon barnebyi</i>) when pressed; staminode exserted, coiled at tip"	13
12	"Anther sacs 0.6--0.7 mm, valves spreading widely; corolla 13--17 mm"	"Penstemon calcareus"
12	"Anther sacs 1.1--1.4 mm, valves barely spreading; corolla 15--20 mm"	"Penstemon monoensis"
13	"Corolla 10--14 mm, throat 4--5 mm wide when pressed"	"Penstemon barnebyi"
13	"Corolla 18--28 mm, throat 7--12 mm wide when pressed"	"Penstemon janishiae"
14	"Inflorescence glabrous; leaf margin generally entire (serrate)"	15
14	"Inflorescence generally glandular or glandular-hairy (except occasionally <i>Penstemon stephensii</i> inflorescence glabrous); leaf margin +- serrate or dentate (except <i>Penstemon heterodoxus</i>, <i>Penstemon incertus</i>, occasionally <i>Penstemon clevelandii</i>)"	30
15	"Corolla 17--34 mm"	16
15	"Corolla 6--17 mm"	23
16	"Anther sacs 0.6--1.2 mm; corolla floor glabrous"	17
16	"Anther sacs 1.2--2.4 mm; corolla floor glabrous or hairy"	19
17	"Corolla generally 13--20 mm, moderately expanded, lavender, magenta, or violet"	"Penstemon patens"
17	"Corolla 17--30 mm, cylindric or narrowly funnel-shaped, pink to red (+- purple)"	18
18	"Corolla lobes projecting, not spreading, glabrous; leaves cordate-clasping"	"Penstemon centranthifolius"
18	"Corolla lobes spreading, glandular; leaves not cordate-clasping"	"Penstemon utahensis"
19	"Distal leaf pairs fused around stem, sharply serrate"	20
19	"Leaf pairs free (or barely fused in some hybrids), entire or weakly serrate"	21
20	"Corolla 19--22 mm, bright pink; anther-sacs 1.3--1.6 mm"	"Penstemon clevelandii var. connatus"
20	"Corolla 24--34 mm, blue-purple or blue; anther-sacs 1.8--2.4 mm"	"Penstemon spectabilis var. spectabilis"
21	"Leaves lanceolate to ovate, 10--35 mm wide; staminode included, glabrous --- common hybrid (see <i>penstemon centranthifolius</i> description)"	"Penstemon hybrid"
21	"Leaves linear to narrowly lanceolate, 3--9 mm wide; staminode exserted, densely hairy"	22
22	"Corolla 22--24 mm, throat 8--10 mm wide when pressed, glandular outside; calyx lobes ovate, generally 5--7.5 mm"	"Penstemon fruticiformis var. amargosae"
22	"Corolla 24--28 mm, throat 10--14 mm wide when pressed, glabrous outside; calyx lobes widely ovate to +- round, generally 4.5--6 mm"	"Penstemon fruticiformis var. fruticiformis"
23	"Openly branched shrub; leaves narrowly linear, generally rolled upward, generally < 1.4 mm wide"	"Penstemon thurberi"
23	"Perennial herb, flowering stems generally little-branched; leaves generally lanceolate to oblanceolate to ovate (+- linear in <i>Penstemon cinicola</i>), flat to folded, 1--22 mm wide"	24
24	"Leaves thick; anther sacs 1--1.2 mm; corolla floor glabrous"	"Penstemon patens"
24	"Leaves +- thin; anther sacs 0.3--1 mm; corolla floor hairy"	25
25	"Corolla 9--17 mm (if < 10 mm anther sacs 0.5--0.8 mm)"	26
25	"Corolla 6--10 mm; anther sacs 0.3--0.5 mm"	28
26	"Plant 8--12 cm; distal cauline leaves ovate to +- round, 10--20 mm; anther sacs +- 0.4 mm; calyx 2.5--3 mm"	"Penstemon tracyi"
26	"Plant 15--60 cm; distal cauline leaves (ob)lanceolate, 15--70 mm; anther sacs 0.5--1 mm; calyx 3--5 mm"	27
27	"Stem base generally buried in sand; proximal-most cauline leaves scale-like"	"Penstemon albomarginatus"
27	"Stem base above ground; proximal cauline leaves well developed"	"Penstemon rydbergii var. oreocharis"
28	"Leaves generally all cauline, +- linear, folded lengthwise and arching-recurved"	"Penstemon cinicola"
28	"Leaves best developed on basal, sterile stems, (ob)lanceolate to obovate, cauline leaves ascending, not arching-recurved"	29
29	"Plant 10--40 cm; distal cauline leaves 10--45 mm, 3--10 mm wide"	"Penstemon procerus var. brachyanthus"
29	"Plant 5--12 cm; distal cauline leaves generally 5--20 mm, 1--5.5 mm wide"	"Penstemon procerus var. formosus"
30	"Distal leaf pairs fused around stem"	31
30	"Leaves free, not fused around stem"	35
31	"Anther sacs 0.8--1.3 mm, valves spreading flat --- desert areas"	32
31	"Anther sacs 1.3--2.4 mm, valves hardly spreading (except <i>Penstemon bicolor</i>)"	33
32	"Corolla generally 17--25 mm, throat 5--9 mm wide when pressed; lower lip strongly lined; anther sacs 1.1--1.3 mm"	"Penstemon pseudospectabilis"
32	"Corolla generally < 20 mm, throat 4--6 mm wide when pressed, lower lip lacking prominent guide-lines; anther sacs 0.8--1.1 mm"	"Penstemon stephensii"
33	"Corolla 18--24(27) mm; anther sacs 1.3--2 mm"	"Penstemon bicolor"
33	"Corolla 24--34 mm; anther sacs 1.8--2.4 mm"	34
34	"Corolla pale pink to lavender-pink; staminode densely hairy, exserted"	"Penstemon palmeri var. palmeri"
34	"Corolla blue-purple or blue; staminode glabrous, included"	"Penstemon spectabilis var. subviscosus"
35	"Corolla 10--18 mm"	36
35	"Corolla 18--35 mm"	39
36	"Leaves +- serrate, distal cordate-clasping; upper side of corolla abruptly expanded"	"Penstemon anguineus"
36	"Leaves entire, distal not cordate-clasping; upper side of corolla cylindric to moderately expanded"	37
37	"Plant 5--20 cm; inflorescence of 1(2) flower clusters"	"Penstemon heterodoxus var. heterodoxus"
37	"Plant generally > 20 cm; inflorescence generally of 2--6 flower clusters"	38
38	"Inflorescence strongly glandular"	"Penstemon heterodoxus var. cephalophorus"
38	"Inflorescence moderately glandular"	"Penstemon heterodoxus var. shastensis"
39	"Leaves thin; upper side of corolla tube abruptly expanded; calyx 6--12 mm"	40
39	"Leaves thick; corolla gradually expanded or lower side +- abruptly expanded; calyx 3--8.5 mm"	41
40	"Calyx lobes ovate, obtuse or rounded at tip, calyx 6--7 mm"	"Penstemon rattanii var. kleei"
40	"Calyx lobes lanceolate, acute or long-tapered at tip, calyx 6--12 mm"	"Penstemon rattanii var. rattanii"
41	"Leaves linear to narrowly lanceolate, 1.5--7 mm wide"	"Penstemon incertus"
41	"Leaves lanceolate to widely ovate, 10--60 mm wide"	42
42	"Corolla gradually expanded, throat 4.5--9 mm wide when pressed"	43
42	"Corolla abruptly expanded (except <i>Penstemon floridus</i> var. <i>austinii</i>), throat 6--20 mm wide when pressed"	45
43	"Corolla 24--30 mm; anther sacs 1.2--1.6 mm; main upper leaves 45--90 mm --- common hybrid (see <i>penstemon centranthifolius</i> description)"	"Penstemon hybrid"
43	"Corolla 18--24 mm; anther sacs 0.8--1.3 mm; main distal leaves 20--60 mm"	44
44	"Leaves entire to moderately serrate; staminode glabrous or sparsely hairy"	"Penstemon clevelandii var. clevelandii"
44	"Leaves sharply serrate; staminode densely hairy"	"Penstemon clevelandii var. mohavensis"
45	"Staminode included, glabrous; anther-sacs 1.3--1.9 mm"	46
45	"Staminode exserted, densely hairy; anther-sacs 1.6--2.2 mm"	47
46	"Corolla 21--27 mm, throat 6--11 mm wide when pressed, mouth perpendicular to tube, tube 6--8 mm"	"Penstemon floridus var. austinii"
46	"Corolla 24--30 mm, +- abruptly expanded to throat, 10--16 mm wide when pressed, mouth oblique to tube, tube 7--12 mm"	"Penstemon floridus var. floridus"
47	"Plant 10--60 cm; young branches light green; corolla 22--30 mm, +- white, tinged pink or lavender"	"Penstemon grinnellii var. grinnellii"
47	"Plant 45--85 cm; young branches glaucous; corolla 26--35 mm, blue-violet"	"Penstemon grinnellii var. scrophularioides"