It’s been at least a month since I’ve shared a Lensbaby photograph, so I suppose I can sneak a couple in today.
Colletia hystrix is commonly known as crucifixion thorn or barbed wire bush. If you discount the cacti in UBC Botanical Garden, then this species competes with Erinacea anthyllis for the title of “most likely to puncture skin if handled carelessly”. Its photosynthetic thorns are viciously sharp, which, as you can see, makes it difficult to smell the small, fragrant flowers.
The species is native to Chile and Argentina. The cultivar ‘Rosea’ is so named because of the pink buds which gradually fade as the flower matures.
Colletia and other closely related genera in the Rhamnaceae (and the not-as-closely related Ceanothus) are actinorhizal, i.e., they have nitrogen-fixing root nodules formed in association with Actinobacteria. This phenomenon is summarized by Luis Gabriel Wall in The Actinorhizal Symbiosis – Plant Communication with Other Organisms – Chemicals are the Words from the Journal of Plant Growth Regulation in 2000 (19 (2): 167-182).
Horticulture / agriculture / history resource links: In a tangential response to this question about Eucalyptus in and around San Diego, a few interesting links were uncovered about eucalypts in California: San Diego’s Eucalyptus Bubble by Leland G. Stanford in the Journal of San Diego History and The Eucalyptus of California: Seeds of Good or Seeds of Evil? by Robert L. Santos, Librarian / Archivist at California State University, Stanislaus. Thanks to Aussiebob on the UBC Forums for the second link.