FLOWERING PLANTS AND FERNS OF ARIZONA 221 



ovate-lanceolate, acuminate, serrate; staminate flowers in long 

 drooping catkins; pistillate flowers solitary, or very few in a cluster; 

 fruit a large, usually nearly globular, hard-shelled nut enclosed in a 

 finally dry husk ; cotyledons 2-lobed. 



The native walnut or nogal is a fine shade tree. The small, thick- 

 shelled nuts are eaten by the Indians in New Mexico and probably 

 in Arizona. Other species of walnut have been employed medicinally 

 and as insecticides, and it is probable that the native species has 

 similar properties. The wood is reported to be durable but is little 

 used . 



1. Juglans rupestris Engelm. in Sitgreaves, Zuni and Colo. Rpt. 171. 

 1854. 



Almost throughout the State, 3,500 to 6,800 feet, along streams, 

 commonly with cottonwood (Populus fremontii) and buttonwood or 

 sycamore (Platanus wrightii). New Mexico, Arizona, and northern 

 Mexico. 



A tree up to 15 m. (50 feet) high and 1.2 m. (4 feet) in trunk 

 diameter but usually smaller, with mostly widely spreading branches. 

 The Arizona walnut is var. major Torr. (J. major Heller), with larger, 

 more coarsely serrate, and commonly more numerous leaflets than in 

 typical J. rupestris, which does not extend so far west. The segregate 

 species published by L. A. Dode, 3 of which are represented by 

 collections in Arizona, are of doubtful validity. The most distinct 

 is J. elaeopyron Dode (type from the Santa Rita Mountains, Pringle 

 in 1881), with a more elongate nut than is usual in this species, but 

 it may be merely an individual variation. 



24. BETULACEAE. Birch family 



Trees or large shrubs ; leaves simple ; flowers monoecious, appearing 

 with or before the leaves, those of both sexes in catkins, the staminate 

 catkins pendulous, the pistillate flowers subtended by conspicuous 

 bracts; ovary 2-celled; fruit a 1-seeded nutlet. 



Key to the genera 



1. Nutlets wingless, each enclosed in a large, bladderlike, papery bract; staminate 



flower solitary in the axil of each scale 1. Ostrya. 



1. Nutlets winged, not enclosed in a bladderlike bract; staminate flowers more 

 than one in the axil of each scale (2) . 

 2. Pistillate catkins solitary, their scales remaining thin, deciduous with or 

 soon after the nutlets, not wedge-shaped, deeply 3-lobed, the midlobe 



elongate 2. Betula. 



2. Pistillate catkins usually several in a racemelike cluster, their scales becoming 

 thick and woody, long-persistent on the branch after the nutlets have 

 fallen, wedge-shaped, shallowly 3- to 5-lobed 3. Alnus. 



1. OSTRYA. Hophornbeam 



Leaf blades ovate, sharply double-serrate; stamens several; stylo 

 slender; stigmas 2, subulate; bracts much enlarged and bladderlike in 

 fruit; nutlets sessile at the base of the bracts. 



1. Ostrya knowltoni Coville, Gard. and Forest 7: 114. 1804 



Grand Canyon and Oak Creek (Coconino County), 5,000 to 7.000 

 feet, type from the Grand Canyon (Tourney 272). Southeast ern Utah 

 and northern Arizona. 



