| Plantaginaceae | |
Penstemon caespitosus subsp. caespitosus
| | | |
| Plantaginaceae | |
Penstemon caespitosus var. caespitosus
| | | |
| Plantaginaceae | |
Penstemon caespitosus subsp. desertipicti
| (A. Nelson) D.D. Keck | Bull. Torrey Bot. Club 64(6): 365 | 1937 |
| Plantaginaceae | |
Penstemon caespitosus var. desertipicti
| (A. Nelson) N.H. Holmgren | Brittonia 31(1): 104 | 1979 |
| Plantaginaceae | ** |
Penstemon caespitosus var. humifusus
| R.A. Nelson | Publ. Univ. Wyoming 3(4): 104–105 | 1937 |
| Plantaginaceae | |
Penstemon caespitosus subsp. perbrevis
| Pennell | Contr. U.S. Natl. Herb. 20(9): 375 | 1920 |
| Plantaginaceae | |
Penstemon caespitosus var. perbrevis
| (Pennell) N.H. Holmgren | Brittonia 31(1): 104 | 1979 |
| Plantaginaceae | |
Penstemon caespitosus subsp. procumbens
| | | |
| Plantaginaceae | |
Penstemon caespitosus subsp. suffruticosus
| (A. Gray) D.D. Keck | Bull. Torrey Bot. Club 64(6): 365 | 1937 |
| Plantaginaceae | |
Penstemon caespitosus var. suffruticosus
| A. Gray | Syn. Fl. N. Amer. 2(1): 270 | 1878 |
| Plantaginaceae | |
Penstemon caespitosus var. thompsoniae
| (A. Gray) A. Nelson | Publ. Univ. Wyoming 3(4): 104 | 1937 |
| Plantaginaceae | ** |
Penstemon caespitosus var. typicus
| D.D. Keck | Bull. Torrey Bot. Club 64(6): 363 | 1937 |