392 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



and creambush. Occurs in Arizona in two forms: (1) var. dumosus 

 (Nutt.) Dippel (H. dumosus Heller, Sericotheca dumosa Rydb.) with 

 leaf blades seldom less than 2 cm. long, normally densely white- 

 sericeous beneath, the inflorescence an ample much-branched panicle; 

 and (2) var. glabrescens (Greenman) Jepson (H. glabrescens Heller, 

 Sericotheca glabrescens Rydb.) a smaller shrub with leaf blades smaller, 

 their lower surface green and glabrate or loosely villous on the veins 

 and granular, the inflorescence racemose or a reduced panicle. The 

 var. glabrescens occurs in Arizona only in the northern part and is most 

 abundant in the Grand Canyon region. 



6. SORBUS. 58 Mountain-ash 



A shrub commonly about 2.5 m. high; leaves odd-pinnate, the 

 leaflets numerous, lanceolate, sharply serrate; flowers small, in ter- 

 minal compound cymes; petals white; stamens many; pistil one, 

 compound, the styles usually 3, the ovary inferior; fruit a small, 

 berrylike pome. 



The plants are favorite cultivated ornamentals, because of their 

 attractive foliage and highly colored, usually bright-red, mature 

 fruits, which are much relished by birds and other wild animals. 

 Some species are small trees. The bark of Sorbus americana Marshall, 

 of eastern North America, is used medicinally for its tonic, astringent, 

 and antiseptic properties. 



1. Sorbus dumosa Greene, Pittonia 4: 129. 1900. 



Apache, Navajo, and Coconino Counties, south to Cochise and 

 Pima Counties, 8,000 to 10,000 feet, moist rich soil of coniferous 

 forests, June and July, type from the San Francisco Peaks (Greene 

 in 1889). New Mexico and Arizona. 



7. AMELANCHIER. Serviceberry 



Large shrubs or small trees; leaves simple, petioled, the blades 

 serrate, dentate, or nearly entire; flowers rather large, in few-flowered 

 racemes or fascicles, seldom solitary; calyx lobes narrow, reflexed; 

 petals rather large, oblong or narrowly obovate, white; stamens 

 numerous; pistil 1, compound; styles 2 to 5, separate or more or less 

 connate ; ovary inferior ; fruit a small several-celled pome ; seed solitary 

 in each cell. 



The small applelike fruits are edible, but insipid. The juicy fruits 

 of certain species are esteemed by the Indians and are said to make 

 good jelly. They are greedily devoured by birds and other animals. 

 The plants are said to afford good browse for sheep, goats, and deer, 

 and in spring for cattle. These plants are hosts of the cedar-apple 

 fungus. 



The taxonomy of this genus is in great confusion and the following 

 treatment of the Arizona forms is necessarily tentative. 



Key to the species 



1. Styles normally 2 or 3; fruit at maturity orange or yellow, rather dry and mealy; 

 twigs rigid, the bark soon becoming gray; leaves commonly finely pubescent 

 or subtomentose, at least beneath; hypanthium, calyx lobes, and the top of 

 the ovary commonly pubescent; styles separate to the base or nearly so (2). 



59 Reference: Jones, G. N. a synopsis of the north American species of sorbus. Arnold Arboretum 

 Jour. 20 : 1-43. 1939. 



