Species Identification

Interested in the identification of penstemons? Please select a species then click on submit:

AttributeThe current selection is Penstemon_attenuatus
ClassificationPenstemon Penstemon Penstemon Proceri
GeneralTaper-leaved or Sulphur Penstemon Wide-ranging P. attenuatus is exceedingly variable through four varieties. Further complicating the situation is that where the range of 2 varieties overlap, the 2 may intergrade by hybridization. Keck (1945) hypothesized that the four varieties probably had different progenitors: var. attenuatus from P. albertinus x confertus, giving the yellow and pink coloration mixed with blue hybrid swarms; var. pseudoprocerus from P. albertinus x procerus, giving rise to head-like terminal thyrses: var. militaris from albertinus x globosus, being the source of incompletely opening anther sacs; and var. palustris, of uncertain parentage, but probably a smaller version of var. attenuatus. P. wilcoxii may also be involved in var. attenuatus and may be responsible for some small teeth on the leaf margins. (Strickler, 1997) Blooms: Late spring and early summer.
Anther0.7-1.2 mm (1/8”) long, smooth or lightly velvety, the sacs open full length (not quite full length in var. militaris), spreading opposite and boat-shaped. Strickler, 1997)
StaminodeReaching the orifice, yellow-bearded and expanded at the tip.
LeavesA basal rosette 12 cm (4 3/4”) long and 1/3-1/5 as wide, usually on short stems, mostly lanceolate to ovate, entire, or finely toothed in var. attenuatus, mostly acute tips, smooth to finely fuzzy, stem leaves reduced 8 cm (3”) long & ½-1/6 as wide and bright green.
Stems1-7 dm (4-28”) tall, usually tufted (in cushions, sticky above and smooth below or very finely fuzzy.
InflorescenseGlandular, of 3-7 loose or crowded verticillasters, moderately- to many-flowered.
Corolla14-20 mm (5/8-3/4”) long, but 7-10 mm in var. palustris, blue-purple or violet to pink, yellow or white, lightly bearded on palate, sticky without, expanding gradually, often drooping.
Flower Color
Calyx4-7 mm (about 1/4”) long, sepals entire and usually thin-edged and sharply pointed.
HabitatMeadows, piney woods, and slopes, low elevation to subalpine.
RangeCentral WA and ne OR to w MT, s ID and c WY. subsp. attenuatus (leaves finely toothed, corolla pale blue, blue-violet, sometimes pale yellow, white, pinkish) ne OR, e WA n ID, nw MT , subsp. attenuatus (leaves finely toothed, corolla pale blue, blue-violet, sometimes pale yellow, white, pinkish) ne OR, e WA n ID, nw MT subsp. militaris (Green) Cronquist (corolla deep blue, buds sometimes blue-black, anther pouch-shaped, doesn’t open completely across connective) c & s ID, nearby MT subsp. palustris (Pennell) Cronquist (corolla smaller, 7-10 mm) wet areas of ne OR subsp. pseudosprocerus (Rydberg) Cronquist (globular thryses, corolla blue-purple.