Koeberlinia spinosa
Holacantha emoryi
Common names: ALLTHORN, CROWN-OF-THORNS, CRUCIFIXION-THORN, (CORONA-DE-CRISTO) Arizona desert: (Koeberlinia spinosa). Greenish. May-June. California desert: (Holacantha emoryi). Yellow-green. June-July. Texas desert: (Koeberlinia spinosa). Greenish. May-June. Koeberlinia is Junco family. Holacantha is Simaruba family. Size: From 2 to 10 feet high.
Two intricately branched, thorny shrubs with green bark and leaves reduced to small scales and otherwise resembling each other are both popularly known by the names of Crown-of-thorns and Crucifixion-thorn, although they are not closely related botanically.
Flowers of both are small and inconspicuous, although when the bushes are in full bloom, they are quite noticeable. Even so, it is the unusual and eye-arresting appearance of these shrubs which appear as leafless masses of robust thorns, making them a conspicuous feature of the desert and arousing the interest and curiosity of observers.
In some locations these shrubs are sufficiently abundant to form thickets which repel livestock. Fruits of H. emoryi remain on the plant for years, and it is usually possible to identify each season’s fruit clusters by the degree of weathering. These masses of brown to black fruits are very noticeable and are often mistaken for parasitic growths or the results of a disease. A somewhat similar shrub, sometimes attaining tree size and superficially resembling the Paloverde (see [p. 36]), is the Mohave-thorn (Canotia holocantha). It is found at elevations between 2,500 and 4,500 feet, over much of southern and western Arizona and northern Sonora, and blossoms from May to August.
Franseria dumosa
Common names: BUR-SAGE, BURROWEED, BURROBUSH Arizona desert: (Franseria deltoidea). Greenish. December-April. California desert: (Franseria dumosa). Greenish. April-November. Sunflower family. Size: Up to 3 feet high.
Noticeable because of its ashy foliage, Bur-sage is a low, rounded, white-barked shrub, the several species of which are very common on the dry plains and mesas up to 3,000 feet. The flowers are small, without petals, and colorless inasmuch as they are wind-pollenated and do not need to attract insects.