A couple of announcements before today’s entry: first of all, welcome to Ruth Sanborn, who will be sharing both her photographs and writings with us on Botany Photo of the Day. We’ll get a short bio from Ruth in the near future.
Secondly, for local readers, don’t forget the Indoor Plant Sale tomorrow and Friday here at the garden!
Ruth is responsible for today’s write-up:
Guaiacum coulteri, an endemic Mexican tree species, is the victim of extensive logging in Mexico. Commonly known as the soap bush, Guaiacum coulteri is a relative of the more commonly known creosote bush, Larrea tridentata of arid southwest North America. Both are members of the Zygophyllaceae. Soap bush’s distribution ranges 1,500 km along the western edge of mainland Mexico from southern Sonora to northern Oaxaca. Excessive felling of canopy trees for export quality lumber since 1914 has altered the population structure to understory shrubs, and has also left the population with a patchy distribution. The tree is currently being evaluated for endangered species status on the IUCN Red List (see: Gordon, JE et al. 2005. Guaiacum coulteri: an over-logged dry forest tree of Oaxaca, Mexico. Oryx. 39: 82-85).
This small tree has ornamental value boasting gorgeous sapphire blooms from May to September. It grows to a height of 2-8m (6-25 feet) and can thrive in partial shade to full sun. The water requirements are less clear, as some sources call it a xeriscape specimen while others recommend wet soil. Its native range in Mexico receives between 30 and 100cm (12 to 40 inches) of annual rainfall.
We would like to sincerely thank DarinAZ of the UBC Botanical Garden forums (from Phoenix, Arizona) for posting this exquisite photograph in this thread via the Botany Photo of the Day Submissions Forum.