Folks driving along the desert roads this month may see many small tight masses of purple flowers waving in the breeze. The Desert verbena are at their peak of flowering right now.
Here’s another example of ‘mixed identity’. There are many common names for this plant: Desert verbena, Prairie verbena, Dakota vervain, Davis Mountain mock vervain, and Moradilla. While many common names exist for a particular plant, one can usually rely on a more specific scientific name. Not the case here (again).
Older published widlflower guides list this plant as Verbena wrightii, and a member of the Verbenaceae (or Vervain) family. While our plant of the week is indeed in the Vervain family it’s genus and species names have changed.
Back in the early 1800’s, naturalist Asa Gray named the plant for Charles Wright , a teacher, surveyor, and plant collector, known notably with the Mexican Boundary Survey. However, new molecular research tools in the last decade or so have determined that a few members of the Vervain family have different chromosomes (numbers and sequences) in their chloroplasts, the organelles in plants that are the powerhouse for producing energy (photosynthesis).
Scientists discovered that some genetic information has been transferred between members of the Vervain and Glandularia genus. In other words, members of these two genus and species have hybridized not just once, but possibly three times as these plants spread north from South America.
Although several plants were once classified as Verbena, and still resemble many of that genus, they have been reclassified (1979) based on genetic similarities and differences. The most commonly known reclassified member is that which was known as Verbena wrightii, or Desert Verbena. It is now recognized in the botanical literature and more recent wildlfower guides as Glandularia bipinnatifida. Although there are two subspecies of this plant referenced (G. bipinnatifida var. cilia. and G. bipinnatifida var. bipinnatifida), their taxonomic classifications remain invalidated and both will find them used synonymously for this species. Perhaps more chemical and molecular studies will elucidate any differences that may exist.
Meanwhile, if you get close enough and smell these plants you may or may not be enamored of their fragrance. While many members of the Vervain family and Verbena genus have pleasant scents, this one had to sit outside after I gathered some samples yesterday. 🙂
For those interested in a recent review of the latter issue, see the following reference, “Taxonomy of the GLANDULARIA BIPINNATIFIDA group (Verbemaceae) in the USA”, by Guy Nesum (of Forth Worth!) in Phytoneuron, issue 46, 2010.