“Our Mexican Salvia collections are among the best-curated in the world” By Lyn Loveless
Most gardeners are familiar with plants in the genus Salvia, also known as “sage.” Salvias are one of the showiest and most aromatic of the plants in the mint family, the Lamiaceae. But in addition to the Salvia species commonly seen in cultivation, Salvia is a widespread wild species, with 1024 species found in temperate habitats worldwide.[1] Although the genus Salvia is also diverse in the Mediterranean and Central Asia, it is especially species-rich in Central and South America, where over half the known species (600+) can be found. Mexico, our southern neighbor, has more species of Salvia in its native flora than any other country in the world. In contrast, there are only 15 species of Salvia native to Arizona!
The University of Arizona Herbarium (identified by its acronym, ARIZ) has a very large collection (2387 sheets) of Salvia specimens, more than half of them from Mexico. For Salvia, as for all other plants in the collection, it is an ongoing challenge to ensure that the specimens in the herbarium are correctly identified and annotated with their most current names. This kind of comprehensive assessment of a plant group requires the efforts of someone who is highly trained and very conversant with modern nomenclature for that group. But thanks to an intensive, week-long visit last year by Dr. Jesús González Gallegos, a researcher and plant systematist from the Durango Polytechnic Institute and CIIDIR Unidad Durango (their associated herbarium), ARIZ now possesses one of the best identified and curated collections of Mexican Salvia in the world.
“Dr. González Gallegos approached us about coming to look at our specimens,” said George Ferguson, Collections Manager for ARIZ. “He was a very welcome guest, and impressively knowledgeable. He worked extremely hard for an entire week.” As a specialist on the Mexican species of Salvia, Dr. González Gallegos has published widely on Salvia and on other Mexican species, especially the mints. Dr. González Gallegos is a co-author of a review article examining the “Lamiaceae de México.” His familiarity with this group allowed him to verify and to update the identity of specimens in the ARIZ collection. In addition to finding some collections that were misidentified as Salvia, he annotated 440 collections with newly determined names. In some cases, two previous species were now considered to be a single species. In others, a single species might have been recently divided into two separate species.
González Gallegos also uncovered three special plant specimens within our holdings, unknown to us, that are now identified as “isotypes.” When a botanist decides to name a new species, she must identify a particular physical plant sample that exemplifies the traits that are diagnostic for that species. This one herbarium sheet is called the “type specimen,” or the “holotype.” Additional collections made by the same collector at the same place and time (with the same collection number) are then called “isotypes.” The “type specimen” is the ultimate reference sample that defines a new species, and as such, types and isotypes are particularly important in understanding evolution and diversity within a lineage. Anyone attempting to revise or redefine a set of species must look at the actual types before making such a determination.
The richness of our Mexican Salvia holdings at the University of Arizona is a legacy of past and current collectors who focused on Mexican species. Said Ferguson, “We have large collections from Sonora and Chihuahua because there were lots of people working on the revision of Gentry’s Rio Mayo Plants [2] and making those collections. There were Gentry’s collections, of course, but David Yetman, Paul Martin, Phil Jenkins, Tom Van Devender, Mark Fishbein – they all collected widely. Dr. Charles Mason, herbarium director from 1953 until 1992, contributed collections from Durango, and Dr. Richard Felger made major contributions from Sonora. John and Charlotte Reeder also made many Mexican collections, especially in Oaxaca.” In addition, ARIZ trades specimens with other herbaria, including UNAM, the herbarium (MEXU) of the Universidad Nacional Autonoma de Mexico in Mexico City. We share with them duplicates of samples collected by Arizona botanists, and they return the favor. Thus, samples collected by Mexican botanists are also represented in our holdings. This kind of exchange permits herbaria to have access to a wider range of specimens than just those from our own collectors. It also makes these samples more widely available to botanists for study.
The outcome of this welcome collaboration with Dr. Jesús González Gallego is that the Salvia collections at ARIZ– at least the Mexican specimens – will be particularly helpful to others studying this group, since they have been annotated with such skill.
[1] Plants of the World database, Kew Gardens. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30000096-2
[2] Martin, Paul S., David Yetman, Mark E Fishbein, Philip D Jenkins, Thomas R. Van Devender, Rebecca K. Wilson, editors. 1998. Gentry’s Rio Mayo Plants: The Tropical Deciduous Forest and Environs of Northwest Mexico. The University of Arizona Press.