CRUCIFIXION THORN (HOLACANTHA EMORYI)
Main sources: Shreve, Forrest, 1951, Vegetation of the Sonoran Desert, Washington, D.C., pp. 142-5: Carnegie Institute of Washington Publication 591;
Click on image below to enlarge:
Crucifixion Thorn bears a resemblance to Foothills Paloverde in its leafless and thorny green-stemmed character, but it stands rather more erect and its ultimate branch-thorns are thicker. It is not frequently encountered in our area, but individuals appear in widely scattered locations and it sometimes forms thickets. Its deeply divided leaves are found only on very small plants, never on the new growth of mature ones.
Crucifixion Thorn bears its flowers and fruit in large clusters near the ends of stems (see left near the top), and each seed becomes encased in a very heavy capsule (see below). Clusters of seeds remain on the tree indefinitely, eventually reaching the ground after 5 to 7 years.
Here is a close-up of flowers blooming in August 2004: (Click on image below to enlarge it):