FLOWERING PLANTS AND FERNS OF ARIZONA 427 



the rudimentary branchlets transformed into spines. A handsomer 

 plant when in flower than C. microphyllum, because of the more highly 

 colored flowers. It appears to be less xerophytic and usually grows 

 larger, having a better water supply. It is somewhat earlier flowering 

 than C. microphyllum. 



12. HOFFMANSEGGIA 



Plants perennial, herbaceous or shrubby; leaves bipinnate, the 

 leaflets small; flowers in terminal or lateral racemes, moderately ir- 

 regular; petals yellow; stamens 10, sometimes red; pods flat. 



Key to the species 



1. Plant a shrub; stems erect, virgate, densely puberulent, up to 1.2 m. long; 

 leaves soon deciduous, the pinnae 3, the terminal one much the longest; 

 racemes elongate; pods lunate, 1.5 to 2 cm. long, 5 to 7 mm. wide. 



1. H. MICROPHYLLA. 



1. Plants herbaceous or suffrutescent; stems decumbent or spreading, seldom 



more than 30 cm. long; leaves persistent, the pinnae 5 or more, the terminal 



one not conspicuously longer (2). 



2. Leaflets dotted beneath with conspicuous black glands, the stems, flowers, 



and pods similarly punctate; pods asymmetrically lunate, conspicuously 



wider above the middle; root large, woody, fusiform__ 2. H. jamesii. 



2. Leaflets, etc., not punctate with black glands; pods not or not conspicuously 



wider above the middle; leaves mostly basal (3). 



3. Flowering stems from a thick woody taproot; herbage finely appressed- 



pubescent; petals short-clawed, glandless; pods strongly falcate, often 



forming nearly a semicircle 3. H. drepanocarpa. 



3. Flowering stems from creeping rootstocks; herbage conspicuously glandular 

 in the inflorescence; petals long-clawed, the claws bearing subulate 

 glands; pods moderately falcate to nearly straight. 



4. H. DENSIFLORA 



1. Hoffmanseggia microphylla Torr., U. S. and Mex. Bound. Bot. 58. 



1859. 



Larrea microphylla Britton, North Amer. Fl. 23: 310. 1930, 



Southern Yuma County, in and around the Gila and Tinajas Alt as 

 Mountains, 1,000 feet or lower, dry sandy or rocky mesas and slopes, 

 March to October. Southwestern Arizona, southeastern California, 

 Sonora, and Baja California. 



Very different in appearance from the other Arizona species and 

 much more xerophytic. 



2. Hoffmanseggia jamesii Torr. and Gray, Fl. North Amer. 1: 393. 



1840. 



Larrea jamesii Britton, North Amer. Fl. 23: 316. 1930. 



Apache County to Coconino County, also near Sonoita (Santa Cruz 

 County), 4,800 to 5,500 feet, dry plains and mesas, sometimes with 

 pinyons and junipers, May to August. Kansas and Colorado to 

 Texas and Arizona. 



3. Hoffmanseggia drepanocarpa A. Gray, PL Wright. 1: 58. 1852. 



Larrea drepanocarpa Britton, North Amer. Fl. 23: 312. 1930. 



Coconino, Mohave, Yavapai, Gila, and Cochise Counties, 3,000 to 

 5,000 feet, May to September. Colorado and western Texas to 

 Arizona and Chihuahua. 



