FLOWERING PLANTS AND FERNS OF ARIZONA 815 



This singular species grows in drifting sand, into which many stems 

 penetrate to connect with the long fleshy root. 



27. Penstemon rydbergii A. Nels., Torrev Bot. Club Bui. 25: 281. 



1898. 



North rim of the Grand Canyon, Coconino County {Purchase 

 2902), moist soil, very rare, July, also in the Tunitcha Mountains, 

 San Juan County, New Mexico, so probably in the same range in 

 Apache County, Arizona. Southern Wyoming, Colorado, New 

 Mexico, and northern Arizona. 



The calyx in Arizona specimens is not glabrous as in the typical 

 form but puberulent as in P. aggregatus Pennell, a common plant in 

 Utah. The calyx lobes are likewise more like those of P. aggregatus, 

 but otherwise the Arizona collection must be referred to P. rydbergii. 

 The Arizona locality is distant from the main area of either species. 



28. Penstemon watsoni A. Gray, Syn. Fl. 2 l : 267. 1878. 

 Mokiak Pass, northern Mohave County (E. Palmer 377), rare in 



Arizona. Common in the sagebrush and pinyon belts of Colorado, 

 Utah, and Nevada. 



The plant is herbaceous throughout, with several moderately tall 

 stems arising directly from a crownlike base without forming a basal 

 rosette. The sepals are remarkably small, seldom exceeding 3 mm. 

 in length. 



29. Penstemon linarioides A. Gray in Torr., U. S. and Mex. Bound. 



Bot. 112. 1859. 

 Apache County to Mohave County, south to Cochise, Gila, and 

 Yavapai Counties, 5,000 to 9,000 feet, often on calcareous soil, June 

 to August. Colorado, Utah, New Mexico, and Arizona. 



Key to the subspecies and variety 



1. Leaves principally oblanceolate subsp. maguirei. 



1. Leaves essentially linear (2). 



2. Leaves glabrous var. viridis. 



2. Leaves densely puberulent (3). 



3. Hairs of the leaf fine, erect or retrorsely spreading subsp. sileri. 



3. Hairs of the leaf flattened, closely appressed (4). 



4. Staminode sparsely bearded apically subsp. coloradoensis. 



4. Staminode more densely bearded, with longer hairs, for most of its 

 length (5). 

 5. Stems ascending from a decumbent rootstock; leaves closely over- 

 lapping, heathlike, mostly 1 cm. long__ subsp. compactifolius. 

 5. Stems strictly erect from a compact caudex; leaves more remote, 

 longer subsp. typicus. 



Arizona is the center of greatest diversity in this -variable species, 

 which comprises many subspecies that are both geographically and 

 morphologically separable, but intergrade at their points of contact. 

 Subsp. typicus Keck is found from Apache and Navajo Comities 

 southward to Cochise County and east to New Mexico. Subsp. 

 maguirei Keck is local in the Gila River Valley (Greenlee County) 

 and in adjacent New Mexico. Subsp. compactifolius Keck is locally 

 common in the Flagstaff region. Subsp. coloradoensis (A. Nels.) 

 Keck grows at high elevations in the northeastern corner of the 

 State, at Marsh Pass, Navajo County (Harvey in 1937) and in the 



286744° 42 52 



