68 American Midland Naturalist Monograph No. 4 



above, light yellowish-green below, usually very rough to the touch; flowers 

 greenish, borne singly or in pairs in the leaf-axils; fruits small, cherry-like, 

 at first green, becoming orange-red or yellow, the flesh thin, dry, sweetish, 

 covering a hard seed. (Syn. C reticulata Torr.). 



Hackberry occurs usually in dry gravelly soils in canyons, and it is not 

 common in the western parks. The small cherry-like fruits were eaten by 

 the Indians. 



Occurrence. — ziON, occasional, 4,400 to 5,500 feet: Zion-Mount Carmel highway; 

 Zion Canyon below the Organ; the Narrows trail. GRAND CANYON, occasional in the 

 canyon, 2,500 to 6,000 feet: Indian Gardens (tree form); Bright Angel trail about 

 2 miles below the South Rim; Dripping Spring; Havasu Canyon. 



Buckwheat Family (Polygonaceae) 

 BuCKWHEATBRUSH (Eriogonum Michx.) 



The genus, Eriogonum, is represented in the national parks by a large 

 group of plants, including herbs, shrubs, and part-shrubs. Some of the latter 

 with branched woody bases are included in this account. In all of the more 

 or less woody species the herbage tends to be white-felty or with yellowish 

 tawny felt. Mature leaves of some of the species are often dark green and 

 nearly smooth above, but the young leaves and twigs are always felty. The 

 flowers have no petals but the calyx is a colored cup-like structure resembling 

 a corolla. Several tiny flowers are usually borne together in a small cup-like 

 involucre. These, in turn, may be borne singly or in groups of several along 

 the flowering stems, or they may be clustered together in dense heads. In 

 many of the species, especially the herbaceous, the heads are borne in umbels 

 (umbrella-like clusters) . Most of the species are of little use as forage. 



Field Guide to the Species 



Flower-involucres scattered along the relatively few more or less erect branches or 

 clustered into heads at the ends. 

 Involucres many-flowered, clustered in heads; plants I}/2 to 3 feet high; found 



in the Southwest I. £. fasciculalum. 



Involucres few-flowered, only rarely clustered in heads; plants '/2 to I (or 2) 



feet high; found in Sierra Nevada and Southwest 2. E. iVrighti. 



Flower-involucres scattered along widely spreading branchlets of intricately branched 

 flower-clusters. 



Stems woody above base; flower-clusters distinctly flat-topped; involucres more 



or less woolly 3. E. microihecum. 



Stems woody only at base; flower-clusters not distinctly flat-topped; involucres 

 not hairy or somewhat hairy on margins. 



Branches of flower-clusters rigid, often spine-tipped; low plants 6 to 8 



inches high 4. E. sulcatum. 



Branches of flower-clusters flexuous, not spine-tipped; plants 1 to 2 feet 



high 5. E. plumalella. 



1. Rosemary Buckwheatbrush (Eriogonum jasciculatum Benth. var. 

 polijolium (Benth.) T. 8C G.) . — Flat-topped evergreen bushy shrub 1^/2 to 3 

 feet high, with shreddy bark and clustered leafy stems; herbage grayish; leaves 



