BUCKWHEAT FAMILY 23 



IV. Clastomyelon 



Perennial herbs, with erect stems, divided into many transverse articulations becom- 

 ing externally obvious in old stems. Leaves all basal. Inflorescence virgately branched. 

 Involucres mostly in whorls of 3 at the nodes, each sessile in the axils of a bract, filled 

 and soon ruptured by the many expanding flowers and bractlets, campanulate, not angled, 

 5-parted; calyx rounded at base; pedicels pilose; achenes flask-shaped, trilobate at base. 



Stems usually solitary, simple below, erect, 8-12 dm. high. 80. E. intrafractum. 



1. Eriogonum caespitosum Nutt. Cespitose Eriogonum. Fig. 1349. 



Eriogonum caespitosum Nutt. Journ. Acad. Phila. 7: 50. pi. 8. f. 2. 1834. 



Woody caudex much branched forming low compact mats. Leaves oval or elliptic, 5-10 mm. 



long, densely white-tomentose on both surfaces, short-petioled, more or less revolute ; flowering 



stems scapose without bracts, slender, 2-10 cm. long; involucre solitary, tomentose, the tube 



turbinate, about 3 mm. long, the lobes oblong-linear, longer than the tube, becoming reflexed; 



calyx yellow turning reddish brown in age and 4-5 mm. long, villous below ; filaments in sterile 



flowers 2.5 mm. long, in fruiting flowers 1.5 mm. long, with abortive anthers, pilose; achene 



sparsely pubescent at apex or often glabrous ; styles 1 mm. long, not reflexed. 



Rocky or gravelly, especially volcanic soils, Upper Sonoran to Canadian Zones; Lake and Harney Counties, 

 Oregon, to Modoc County and White Mountains, Inyo County, California, east to Idaho, northern Nevada, 

 Montana, Wyoming, and Colorado. Type locality: headwaters of the Columbia, probably in Idaho. May-Aug. 



2. Eriogonum Douglasii Benth. Douglas' Eriogonum. Fig. 1350. 



Eriogonum Douglasii Benth. in DC. Prod. 14: 9. 1856. 



Eriogonum caespitosum var. Douglasii Jones, Contr. West. Bot. No. 11: 7. 1903. 



Eriogonum nevadense Gandoger, Bull. Soc. Bot. Belg. 42: 188. 1906. 



Woody caudex much branched, forming mats, often 3-4 dm. across. Leaves densely white- 

 tomentose on both surfaces, forming a dense rosette at the end of the branchlets, 4-42 mm. long, 

 obovate to oblanceolate, narrowed at base to a short petiole, rather thick, the margins sometimes 

 slightly revolute ; flowering stems 3-10 cm. long, bearing a whorl of narrowly oblanceolate folia- 

 ceous bracts near the middle ; involucre solitary, the tube narrowly turbinate, 3 mm. long, the lobes 

 oblong, as long as the tube; calyx bright yellow often turning reddish in age, 5-6 mm. long includ- 

 ing the stripe-like base, villous-pubescent without on the midvein and toward the base, and spar- 

 ingly so within; filaments pubescent below; achenes sharply angled, sparingly pubescent above. 



Dry rocky ledges and slopes, Upper Sonoran and Arid Transition Zones; eastern Washington to the central 

 Sierra Nevada, California, and western Nevada. Type locality: Blue Mountains, Oregon. May-Aug. 



3. Eriogonum tenue Small. Klickitat Eriogonum. Fig. 1351. 



Eriogonum tenue Small, Bull. Torrey Club 25: 41. 1906. 



Eriogonum sphaerocephalum tenue Piper, Contr. U.S. Nat. Herb. 11: 236. 1906. 



Cespitose, the woody caudex much branched. Leaves forming rosettes at the ends of the 

 branchlets, narrowly linear, narrowed below, strongly revolute, 5-15 mm. long, cinereous with a 

 dense woolly tomentum on both surfaces ; flowering stems 4-7 cm. high, naked or with a whorl 

 of foliaceous bracts near the middle, tomentose ; involucre without bracts, the lobes linear-oblong, 

 equaling or longer than the tube, reflexed, many-flowered ; calyx ochroleucous, glabrous or nearly 

 so, the lobes oblong-obovate ; filaments 3 mm. long, hairy below; achene 4.5 mm. long including 

 the short beak, short-pubescent above ; styles slender, coiled back, about 2 mm. long. 



Sterile rocky soil, Upper Sonoran Zone; Kittitas County to Klickitat County, eastern Washington. Type 

 locality: "On the Columbia River, in West Klickitat County, Washington." April-June. 



4. Eriogonum sphaerocephalum Dougl. Round-headed Eriogonum. Fig. 1352. 



Eriogonum sphaerocephalum Dougl. ex Benth. Trans. Linn. Soc. 17: 407. 1837. 



Caudex with decumbent loosely cespitose suffruticose branches, 5-10 cm. high. Leaves vertic- 

 illate at the apex and upper node of the branches, narrowly oblanceolate, 1-3 cm. long, floccose 

 or glabrate above, densely white-tomentose beneath, revolute on the margin ; flowering stems erect 

 or ascending, 5-10 cm. long, bearing a verticil of foliaceous bracts above the middle ; involucre 

 solitary, the tube broadly turbinate, the lobes 7-8, linear-oblong, as long or longer than the tube, at 

 length reflexed ; flowers numerous forming a globose head ; calyx cream or yellow, villous-tomen- 

 tose; filaments pubescent below; styles 2.5 mm. long; achene pubescent above. 



Dry rocky places, mainly Upper Sonoran Zone; Kittitas County, Washington, to Siskiyou County, Cali- 

 fornia, east to Idaho and northern Nevada. Type locality: Columbia River, Washington. May-July. 



5. Eriogonum tripodum Greene. Tripod Eriogonum. Fig. 1353. 



Eriogonum tripodum Greene, Pittonia 1: 39. 1887. 



Woody caudex, more loosely branched than the preceding species. Leaves linear-spatulate, 15- 

 25 mm. long, narrowed to a short petiole, white-tomentose on both surfaces, revolute on the 

 margin; flowering stems 18-35 cm. high, slender; umbels 3- rarely 2-rayed, the rays 4—10 cm. long, 

 subtended by a whorl of foliaceous bracts and sometimes bearing a whorl near the middle of one 

 or two of the rays ; involucres solitary, densely tomentose, the lobes linear-oblong, shorter than 



