[Illustration: 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.
[Illustration: 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.
It is classed by A. A. Nichol as one of the major plants of the
Paloverde-Bur-sage-Cacti plant association, one of the three plant
communities of the Sonoran Desert.
Bur-sage is one of the favorite foods of burros and sheep, and is said
to be preferred also by horses.