84 TREES AND SHRUBS 



Flowers solitary at the ends of the branches. 4. R. sayi. 

 Infrastlpular spines present. 

 Sepals not bristly. 



Petioles not glandular, the bracts often 

 glandular toothed. 

 Spines few, stout, strongly curved; leaf- 

 lets pale above, small, thick. 9. R. neomexicana. 

 Spines numerous, slender, straight or 

 nearly so; leaflets bright green 



above, larger, thin. 10. R. maximiliana. 



Petioles strongly glandular. 



Leaves finely pubescent beneath, often 



strongly glandular. 8. R. fendleri. 



2. OPULASTER Medic. 



A low shrub, 3 feet high or less, with exfoliating bark, and 

 white flowers in terminal corymbs; leaves simple, rounded ovate in 

 outline, 3 to 5-lobed, glabrous or nearly so, doubly incised serrate;, 

 flowers small; hypanthium about 3 mm. broad, stellate; petals orbi- 

 cular, about 3 mm. long; follicles 2 or rarely 3, united to above the 

 middle, densely steKate, with spreading beaks. 

 A single species of the Transition Zone. 1. O. monogynus. 



3. PETROPHYTON (Nutt.) Rydb. 



A denseij caespitose and depressed undershrub with pros- 

 trate branches; leaves spatulate, 5 to 12 mm. long, 2 to 4 mm. wide, 

 densely silky; peduncles 1 to 4 inches high, with bract-like, subulate 

 leaves; inflorescence a dense spike of small whitish flowers; sepals 

 ovate-lanceolate, acute, 1.5 mm. long; petals spatulate, obtuse, about 

 the same length; follicles 3 to 5, 2 mm. long. 

 A single species. 1. p. caesptiosum. 



4. BATIDAEA Greene. Raspberry. 



Spiny shrubs 3 feet high or less, with 5- to 7-foliolate leaves, 

 and inconspicuous white flowers; stems of the first season erect, 

 armed with straight prickles; leaves of the flowering branches with 

 fewer leaflets; leaflets ovate to rhombic-lanceolate, serrate, the 

 terminal sometime- lobed. ureen above, densely white-tomentose 

 beneath; fruits brighl red, juicy, with pleasant taste and color. 



1. B. strigosa. 



