26 EUPHORBIACEAE 



3. Ditaxis serrata (Torr.) Heller. Yuma Ditaxis. Fig. 3022. 



Aphora serrata Torr. Bot. Mex. Bound. 197. 1858. 



Ditaxis serrata Heller, Cat. N. Amer. PI. 5. 1900. 



Ditaxis odontophylla Rose & Standley, Contr. U.S. Nat. Herb. 16: 12. 1912. 



Annuals or short-lived perennials, pubescent, 1-2 dm. high, branching from the base, the 

 stems decumbent or prostrate. Leaves 1-3 cm. long, obovate to oblong, obtuse, typically serrate 

 at the apex, densely covered with slender appressed or crinkled hairs mixed with long appressed 

 setose hairs ; racemes congested in the leaf-axils ; staminate flowers 3 mm. long, staminate petals 

 longer than the sepals or equaling them ; pistillate sepals 3.5-5 mm. long, pubescent, attenuate, 

 the white margins inconspicuous ; pistillate petals hairy on the back with pilose and long setose 

 hairs, clawed, the blade deltoid, one-half to more than one-half as long as the calyx ; pistillate 

 gland thin, 0.5 mm. long or less; seeds brownish or grayish, globose-ovoid, nearly smooth, 

 marked with low corrugate reticulations. 



Desert slopes, Lower Sonoran Zone; Colorado Desert, California, south to Lower California and east to 

 southwestern Arizona and Sonora. Type locality: "Fort Yuma, California." April-Sept. 



4. Ditaxis neomexicana (Muell. Arg.) Heller. Con-imon Ditaxis. Fig. 3023. 



Argythamnia neomexicana Muell. Arg. Linnaea 34: 147. 1865. 

 Ditaxis neomexicana Heller, Cat. N. Amer. PL 5. 1898. 



Annuals or short-lived many-stemmed perennials, 1-3.5 dm. high, the branches when present 

 spreading, herbage sometimes purplish. Leaves 1-2.5 cm. long, narrowly or broadly oblanceolate, 

 mostly acute, more or less strigose with setose hairs, the margins entire or serrulate, _ veins 

 prominent on the lower surface at base of leaf; inflorescence few-flowered, congested in the 

 leaf -axils; staminate flowers 1.5-2 mm. long, the petals longer than the sepals; pistillate sepals 

 3.5-5 mm. long, narrowly lanceolate, conspicuously white-margined, occasionally vyith few 

 glandular teeth present on the margins, the external gland-like fold of the white margin at the 

 base of the sepal more or less conspicuous; pistillate petals 1.5-2.5 mm. long, one-half to more 

 than one-half the length of the sepals, more or less hairy on the back, setose hairs occasionally 

 present ; seeds ovoid, brownish, faveolate, depressions marked with minute radiating ridges. 



Desert slopes, Lower Sonoran Zone; Mojave Desert, California, south to Lower California, east to western 

 Texas and south to Sonora. Type locality: New Mexico. March-Dec. 



The plants from western Arizona and from California differ somewhat from typical material but are ex- 

 tremely variable as to density of pubescence and relative lengths of pistillate sepals and petals. 



5. Ditaxis californica (Brandg.) Pax & K. Hoffmn. California Ditaxis. 



Fig. 3024. 



Argythamnia californica Brandg. Zoe 5:230. 1906. 



Ditaxis californica Pax & K. Hoffmn. Pflanzenreich 4i".vi ; 70. 1912. 



Annuals 1.5-3 dm. high with divergent branches, the young growth purplish, glabrous or 

 nearly so. Leaves 2.5-4.5 cm. long, oblanceolate, serrulate, typically glabrous; inflorescence 

 congested ; staminate flowers 2.5 mm. long, the petals equaling or exceeding the sepals ; pistillate 

 sepals linear-attenuate, 3.5-4.5 mm. long, white margins with a few marginal glands, the external 

 gland-like fold of the white margin at the base of the sepal conspicuous ; pistillate petals clawed, 

 broadly deltoid; ovary glabrous or nearly so; seeds brown, faveolate, the depressions more or 

 less marked with minute radiating ridges. 



Desert slopes. Lower Sonoran Zone; rare, in the Coachella and Eagle Mountains, northern Colorado Desert, 

 California. Type locality: near Coachella, California. April-May. 



4. CROTON L. Sp. PI. 1004. 1753. 



Stellate-pubescent, more or less glandular and strong-scented monoecious or dioecious 

 herbs or shrubs, with mostly alternate, entire, toothed or lobed leaves, and monoecious 

 or dioecious flowers in terminal or axillary clusters. Staminate flowers uppermost; calyx 

 usually 5-parted; petals usually present, small or rudimentary, alternating with the 

 glands; stamens 5 or more, inflexed. Pistillate flowers clustered below the staminate; 

 calyx 5-10-parted; petals usually wanting; ovary 3-celled; ovules 1 in each cell; styles 

 once, twice or many times 2-cleft. Capsule splitting into usually 2-valved carpels ; seeds 

 smooth or minutely pitted. [Greek name of the Castor-oil plant.] 



About 600 species of tropical and subtropical regions of the world. Type species, Croton Tiglium L. 



1. Croton californicus Muell. Arg. California Croton. Fig. 3025. 



Croton californicus Muell. Arg. in A. DC. Prod. 12^: 691. 1866. 

 Croton californicus var. major S. Wats. Bot. Calif. 2: 69. 1880. 



Erect or spreading sufifrutescent dioecious perennials, 2-10 dm. high, with a stellate scurfy 

 pubescence throughout. Leaf-blades entire, 1.5-5 cm. long, oblong, petioles slender, 1-3 cm. long, 

 pubescence more sparse above; pistillate infloresence few-flowered, short-racemose; pistillate 

 flowers 2 mm. long or more, pedicels 2^ mm. long ; staminate inflorescence many-flowered, the 

 raceme elongating in age, staminate flowers about 2 mm. long on slender pedicels 3-4 mm. long, 



