Native Plants

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Sunday - April 01, 2012

From: Austin, TX
Region: Southwest
Topic: Plant Identification
Title: Origin of cultivar of Sophora secundiflora
Answered by: Anne Ruggles

QUESTION:

Howdy, Mr. Smarty Plants! I am hoping you can shed some light on the origin of my silver-leaved TX Mountain Laurel, "Silver Peso". Some nurseries refer to it as a genetic variation of Sophora secundiflora, some refer to it as a cultivar, and still others refer to it as Sophora arizonica, native to Arizona. The NPIN database makes no reference to an Arizonica variety, So I'm wondering what gives? How did this tree come to be? Thanks!

ANSWER:

You have encountered a mash-up of terminology, some of it scientific and some from “common” language. The NPIN database is constantly growing; one day you may find an entry for Sophora arizonica. The short answer to your question is that Sophora arizonica and S. secundaflora are both species native to North America; both with fairly limited ranges. The first has a limited distribution in Arizona and the second is native to Texas, New Mexico, and northern Mexcio.

We went to the USDA (United States Department of Agriculture) Natural Resources Conservation Service, Plants Profile database. This shows that there are 12 species in the genus Sophora in North America. Of those 12, one is S. arizonica (native to Arizona only) and one is S. secundiflora native to Texas and New Mexico.

We also went to the ITIS (Integrated Taxonomic Information System on-line database) Taxonomy working Group web site and accessed the North American database for the family Fabaceae (Sohphora is a member of this family). This database was updated in 2011. It also shows 12 species within the genus and includes both S. arizonica and S. secundiflora.

The Sonoran Desert Naturalist describes the range of S. Arizonica as having a "very restricted range. Isolated populations on eastern and southern foothills of the Hualapai Mts. of Mohave Co. and in portions of Graham and norther Cochise Co., Arizona. A related plant, Texas Sophora (aka Mescal Bean), Sophora secundaflora, is widely cultivated in Phoenix and Tucson xeriscapes." You can find photos of S. arizonica on their web site.

The Wildflower Center, as you have found, has an entry for S. secundaflora.

From the Image Gallery

Texas mountain laurel
Dermatophyllum secundiflorum