FLOWERING PLANTS AND FERNS OF ARIZONA 567 



6. Inflorescence an open, relatively few-flowered panicle. 5. S. laxa. 

 5. Walls of the carpels thicker, chartaceous, the reticulate part with coarser, 



often opaque areolas (7). 



7. Reticulate part of the carpel usually rugose or muricate on the back, 



the reticulations prominent and coarse (8). 

 8. Fruit hemispheric or nearly so; carpels usually muticous or mucronu- 

 late, about two-thirds as wide as high; plant often suffrutescent; 

 leaf blades semiorbicular, shallowly lobed; inflorescence usually 



an open panicle 4. S. ambigua. 



8. Fruit truncate-conic; carpels usually cuspidate, less than two-thirds 

 as wide as high; plant not suffrutescent; leaf blades considerably 

 longer than wide; inflorescence racemiform or narrowly thvrsoid 

 (9). 

 9. Inflorescence a long, many-flowered thyrse with usually more than 

 3 flowers to the node; caudex well developed; stems erect or 

 nearly so, seldom less than 60 cm. long; pedicels usually per- 

 sistent _ 3. S. EMORYI. 



9. Inflorescence racemiform or subthyrsoid with 1 to 3 flowers to the 

 node; caudex usually poorly developed; stems often originating 

 as root shoots, commonly decumbent at base, not more than 

 50 cm. long; pedicels detaching promptly at maturity of the 



fruit _ 11. S. SUBHASTATA. 



7. Reticulate part of the carpel smooth or nearly so on the back, the 



reticulations less prominent and finer (10). 



10. Inflorescence relatively few-flowered, not thyrsoid-glomerate; 



carpels about half as wide as high (11). 



11. Calyx not conspicuously more pubescent than the stems and 



leaves, these commonly densely whitish canescent or tomentose; 



inflorescence an open, long-branched panicle; carpels usually 



acutish, cuspidate, and rather prominently reticulate with 



semitransparent areolas 5. S. laxa. 



11. Calyx conspicuously more pubescent than the stems and leaves, 



tho<e usually green and glabrate; inflorescence typically nar- 

 row and short-branched; carpels mostly very obtuse, muticous 

 or mucronate, and rather faintly reticulate with opaque areolas. 



6. S. rusbyi. 

 10. Inflorescence many- flowered, thyrsoid-glomerate, or, if few-flowered 

 and racemiform, then the carpels much more than half as wide 

 as high (12). 



12. Fruit hemispheric or nearlv so; carpels three-fifths to fullv as wide 



as high (13). 

 13. Leaf blades not pedate, shallowly lobed near the middle with 

 broad, rounded lobes, broadly deltoid or suborbicular, more 

 or less cordate, thickish, the veins prominent beneath. 



12. S. PARVIFOLIA. 



13. Leaf blades pedately cleft, parted, or divided (14). 



14. Inflorescence a narrow, interrupted, many-flowered thyrse; 

 leaf blades with a midlobe 10 to 20 mm. wide. 



13. S. GROSSULARIAEFOLIA. 



14. Inflorescence racemiform or subthyrsoid, few-flowered; 

 leaf blades with midlobe not more than o mm. wide. 



14. S. DIGITATA. 



12. Fruit truncate-conic; carpels half to three-fifths as wide as high 



(15). 



15. Blades about equally long and wide, shallowly lobed, usually 



cordate; pubescence grayish or whitish__ 12. S. parvifolia. 



15. Blades much longer than wide or, if not much longer, then 



either pedate, or cuneate at base, or the pubescence vellow- 



ish (16). 



16. Blades pedatelv cleft or parted 7. S. wrightii. 



16. Blades not pedate (17). 



17. Blades merely angulate or toothed near the base, linear- 

 lanceolate or oblong-lanceolate, not more than one- 

 third as wide as long; pubescence grayish. 



10. S. ANGUSTIFOLIA. 



