FLOWERING PLANTS AND FERNS OF ARIZONA 377 



3. Echeveria arizonica (Rose) Kearney and Peebles, Wash. Acad. 



Sci. Jour. 29: 479. 1939. 



Dudleya arizonica Rose, Addisonia 8: 35. 1923. 



Maricopa, Mohaye, and Yuma Counties, 500 to 2,500 feet, on cliffs, 

 April, October, and December, type from Yucca, Mohave County 

 (Bly in 1921). Known only from western Arizona. 



Related to Echeveria pvlvendenta Nutt. of southern California, but 

 the plant is smaller and less pulverulent, with smaller flowers. 



4. Echeveria collomae (Rose) Kearney and Peebles, Wash. Acad. 



Sci. Jour. 29: 479. 1939. 



Dudleya collomae Rose ex Morton, Desert Plant Life 6: 68. 

 1934. 



Yavapai, Gila, Maricopa, and Pinal Counties, 2,000 to 6,000 feet, 

 among rocks, March to May, type from near Payson, Gila County 

 (Collom in 1924). Known only from central Arizona. 



This, the showiest and commonest Echeveria of Arizona, is handsome 

 in flower and well worthy of cultivation. It is closely related to several 

 California species and was presumably included under Dudleya 

 parishii Rose in North American Flora (22: 41. 1905). M. E. 

 Jones referred this form to his Cotyledon saxosum (Dudleya saxosa 

 Britton and Rose, Echeveria saxosa Nels. and Macbr.), the type of 

 which, a smaller plant, was collected in the Panamint Mountains, 

 Calif. 



3. TILLAEA. Pigmyweed 



Plant annual, not more than 10 cm. high, glabrous, soon becoming 

 reddish brown; stems slender, branched, winged; leaves opposite, 

 connate-perfoliate; flowers minute, in small axillary clusters; sepals, 

 petals, and stamens usually 4; seeds 1 or 2 in each follicle. 



1. Tillaea erecta Hook, and Arm, Bot. Beechey Yoy. 24. 1830. 



Maricopa, Pinal, and Pima Counties, 1,500 to 4,000 feet, March and 

 April. Oregon to Baja California and southern Arizona; Chile. 



Saxifrage family 



Plants perennial, herbaceous or shrubby; leaves simple, alternate, 

 opposite, or mostly basal; flowers perfect or some of them unisexual, 

 regular or nearly so, in racemes, cymes, or panicles, usually with a 

 well-developed hypanthium and often with a disk; sepals and petals 

 usually 5, the petals rarely wanting; stamens 4 to 12; pistil 1 and com- 

 pound, or in some genera of 2 nearly separate carpels; ovary inferior, 

 or nearly free from the calyx; fruit follicular, capsular, or baccate. 



The best-known members of this family are the currants and goose- 

 berries. It includes many species, both herbaceous and shrubby, that 

 are highly esteemed as cultivated ornamentals. 



Key to the genera 

 1. Plants herbaceous (2). 



2. Fertile stamens 10; staminodia none (3). 



3. Styles 2; capsule 2-celled and 2-beaked, the carpels sometimes nearly 



separate; petals entire or nearly so 1 . Saxifraga. 



3. Styles 3; capsule 1-celled, 3-valved, not beaked; petals usually laciniate or 

 deeplv dentate 3. Lithophr.u; m a. 



