SCROPHULARIACEAE. 



VOL. III. 



9. PENTSTEMON Mitchell; Soland. in Ait. Hort. Kew. 3: 511. 1789. 



Perennial herbs, mostly branched from the base only, with opposite or rarely verticillate 

 leaves, or the upper occasionally alternate, and large, usually showy, blue purple red or white 

 flowers, in terminal thyrses, panicles, or racemes. Calyx 5-parted, the segments imbricated. 

 Corolla irregular, the tube elongated, more or less enlarged above, the limb 2-lipped ; upper 

 lip 2-lobed; lower lop 3-lobed. Stamens 5, included, 4 of them antheriferous and didy- 

 namous, the fifth sterile, as long as or shorter than the others; anther-sacs divergent or 

 connivent. Style filiform; stigma capitate. Capsule ovoid, oblong, or globose, septicidally 

 dehiscent. Seeds numerous, angled or even, wingless. [Greek, five stamens.] 



About 100 species, natives of North America and Mexico. Type species: Pentstemon pubes- 

 cens Soland. 



* More or less pubescent or glandular, at least the calyx and pedicels. 



Corolla J^' i J4' long; leaves entire, serrate, or denticulate. 

 Stem pubescent or puberulent nearly or quite to the base. 

 Thyrsus open, panicle-like. 



Corolla large, over 10" long; stem hirsute or canescent, often glandular. 



Corolla densely bearded in the throat ; outer calyx-segments ovate or ovate-lanceolate. 



i. P. hirsutus. 



Corolla scarcely bearded in the throat ; outer calyx-segments lanceolate or linear- 

 lanceolate. 2. P. canescens. 

 Corolla small, less than 10" long; stem puberulent. 3. P. pallidus. 

 Thyrsus narrow, raceme-like or spike-like. 



Corolla-tube abruptly enlarged ; sterile filament densely woolly. 4. P. erianthera. 



Corolla-tube gradually enlarged; sterile filament slightly bearded. 5. P.albidus. 



Only the inflorescence, or pedicels, or calyx pubescent. 

 Thyrsus open, panicle-like. 



Stem leaves oblong, ovate, or lanceolate. 



Calyx-lobes lanceolate to ovate, much less than 5" long. 



Corolla purplish ; tube not gibbous above the point of enlargement. 



6. P. Pentstemon. 

 Corolla white or pinkish ; tube gibbous above the point of enlargement. 



7. P. Digitalis. 

 Calyx-lobes linear-subulate from a narrowly lanceolate base, becoming fully 5" long. 



8. P. calycosus. 

 Stem leaves linear-lanceolate. 9- P- gracilis. 



Thyrsus narrow, interrupted; calyx viscid. 10. P. tubiflonts. 



Corolla 2.' long, the tube much enlarged above; leaves dentate. n. P. Cobaea. 



** Completely glabrous throughout, mostly glaucous. 



Leaves lanceolate, oblong, ovate, obovate, or orbicular. 

 Stem leaves rounded, clasping ; flowers 2' long. 

 Stem leaves acute or acuminate; flowers 9"-is" long. 

 Corolla 9" 10" long; stem leaves lanceolate. 

 Corolla i'-i l /2 r long; stem leaves mostly oblong. 

 Leaves linear or linear-lanceolate ; flowers densely thyrsoid. 

 Bracts lanceolate, small ; flowers 6"-8" long. 

 Bracts ovate, acuminate, large; flowers i' long or more. 



12. P. grandiflorus. 



13. P. acuniinatus. 



14. P. glaber. 



15. P. angustifolius. 



1 6. P. Haydeni. 



i. Pentstemon hirsutus (L.) Willd. 

 Hairy Beard-tongue. Fig. 3755. 



Chelone hirsuta L. Sp. PI. 611. 1753- 



P. pubescens Soland. in Ait. Hort. Kew. 3 : 360. 1789. 



Pentstemon hirsulus Willd. Sp. PI. 3: 227. 1801. 



Stem slender, erect, downy nearly or quite to 

 the base, i-3 high. Leaves puberulent or gla- 

 brous, denticulate or the uppermost entire,^ the 

 basal oblong or ovate, obtusish at the apex, 2'-4i' 

 long, i'-a' wide, narrowed into petioles, the up- 

 per sessile, lanceolate, mostly acuminate, sessile 

 or slightly clasping ; inflorescence thyrsoid, rather 

 loose, glandular-pubescent ; pedicels mostly short ; 

 corolla purplish or violet, the tube gradually 

 dilated above, 2-grooved on the lower side, about 

 i' long, the throat nearly closed by the villous 

 palate at the base of the lower lip; sterile fila- 

 ment densely bearded for about one-half its 

 length. 



In dry woods and thickets, Maine to Ontario, 

 Florida, Minnesota, Alabama and Missouri. Er- 

 roneously recorded from Texas. May-July. 



