Addisonia ' 79 



(Plate 160) 

 PENSTEMON TENUIFLORUS 



Slender-flowered White Beard-tongue 



Native of the central Mississippi Valley 



Family ScrophuIvAriac^a© Figwort Family 



Penstemon tenuifiorus Pennell, sp. nov. 



A finely pubescent herbaceous plant, from a short rootstock 

 sending up usually but one stem, terminating in a panicle of very 

 slender white flowers. The erect stems, finely pubescent with 

 scattered minute white hairs, are one to two feet tall. The leaves 

 of the winter rosette, persisting at the base of the stem until the 

 flowering season, are about four inches long, the petiole nearly 

 equaling the ovate blade ; the stem-leaves are lanceolate and sessile, 

 clasping by a rounded base; all are softly pubescent with minute 

 rather sparse hairs, light green, scarcely paler beneath, and with 

 obscurely serrulate margins. The panicle, less than one third the 

 height of the plant, is rather secund, lax and composed of but three 

 or four nodes; the branching is as in P. Digitalis (pi.atk 130); its 

 bracts throughout are very much smaller than the leaves and not at 

 all conspicuous; stems, pedicels, and calyces are pubescent with 

 gland-tipped hairs. The peduncles are usually well developed, 

 frequently an inch in length, although the pedicels are short. 

 The sepals are ovate, acute, with slightly erose scarious margins, 

 and are about one seventh of an inch long. The corolla is slightly 

 over one inch long, its form as narrow as in P, hirsutus (plate 45) ; 

 its throat is gradually slightly inflated, narrowly arched and keeled 

 above, flattened and strongly two-ridged within, while at its mouth 

 it is nearly closed by the upraised base of the anterior lip; the pos- 

 terior lip is formed of two lobes which are united and arched about 

 two thirds their length, beyond which their free portions are erect- 

 recurved; the anterior lobes are longer, spreading; the corolla is 

 white, only faintly tinged externally and on the margins of the lobes 

 with violet, and has no lines of deep color within the throat ; ex- 

 ternally it is finely pubescent with gland-tipped hairs, and within, 

 over the bases of the anterior lobes and on the two ridges within 

 the throat, it is strongly pubescent with yellow hairs. The stamens 

 are essentially as in P. hirsutus, the anther-sacs narrower and always 

 glabrous. The sterile filament is densely bearded distally with 

 short lemon-yellow hairs. The capsule has not been seen. 



The type specimen was collected in loam soil in open pineland, 

 three miles southeast of Albany, Morgan County, Alabama, on 

 May 27, 1917, my number 9753, and is preserved in the herbarium 

 of the New York Botanical Garden. The species is known to occur 

 from Illinois to northern Alabama, and in central Oklahoma. 



