three illustrations of
cottsia gracilis, slender janusia

When you first see Margaret Pope’s illustration of Calliandra eriophylla, you’ll likely be drawn to the fairy duster’s flashy pink flowers, and you might not notice the small vine climbing and twisting itself around the shrub’s branches. This tough little plant is slender janusia (Cottsia gracilis, previously Janusia gracilis), one of only three species in the genus Cottsia, all of which can be found in the Sonoran Desert.

From April to October, the vine’s bright yellow flowers attract oil-collecting bees that use their hind legs to scrape oil from the glands on the undersides of the sepals, pollinating the flower in the process. This method of attracting pollinators is common among the New World species of Malpighiaceae, the Barbados cherry family, of which the genus Cottsia is a member.

Slender janusia’s fruit is a samara, a winged seed pod somewhat similar to a maple seed. In this case, it is a three-winged fruit that turns a reddish-bronze color when mature (see the lower left of Margaret’s illustration).

The second illustration shown here is an enlargement of slender janusia’s flower. The five spoon-shaped petals are bright yellow and slightly wrinkled with uneven edges, each roughly 1/4” long. As the petals age, they turn reddish-orange. Between each petal, you can see the sepals below, each with a pair of tiny oil glands.

This illustration of the janusia flower was painted by Philip Jenkins, the former curatorial specialist at the University of Arizona Herbarium who passed away in February of last year. His illustration was incorporated into the new logo for the Herbarium that was designed by Shelley McMahon, the Herbarium’s Director.

Phil spent many years working for the Forest Service, first in Washington and eventually in Arizona. He received bachelor's and master's degrees in biology from the University of Arizona and worked for the Herbarium from 1992 to 2011. Phil was a skilled botanical illustrator, and after his retirement from the Herbarium, he graciously agreed to make occasional visits to Margaret Pope’s ‘Drawing Plants for a Florilegium’ class at the Desert Museum's Art Institute. We all benefitted from his vast knowledge and his patient explanation of the various structures of the plants we were drawing.

The Herbarium’s website has an excellent page dedicated to the development and significance of their logo, including a description of Cottsia gracilis and an explanation of the origin of the name ‘Janusia’. It’s gratifying to see a highly detailed and accurate botanical illustration used to such wonderful effect in a logo.

The third illustration shown here was the first scientific botanical illustration of Cottsia gracilis, then named Janusia gracilis by the botanist Asa Gray. The drawing was prepared for the Pacific Railroad Survey Report for the proposed route from San Francisco to the Rio Grande. The specimen used for the illustration had been collected by the naturalist Charles Wright in the Burro Mountains of New Mexico in August of 1849 when the plant was in bloom. Also used to prepare the illustration was a fruiting specimen from the collection of Dr. John Milton Bigelow. Wright and Bigelow were both naturalists who served with the U.S.–Mexico Boundary Survey in 1850–1851.

A note about the tangled history of the names Cottsia and Janusia:
The name Cottsia originated with two French botanists, Paul Dop and Marcel Dubard, in 1908. An unknown specimen they were examining was labeled as having been collected in Madagascar, so they devised an anagram based on the name of the Scottish botanist George Francis Scott-Elliot who had spent several years botanizing in Madagascar and Africa. They applied their anagram honoring Scott-Elliot to the genus of the plant at hand, Cottsia scandens. As it turned out, their specimen had been mislabeled and had not been collected in Madagascar but rather in Guaymas, Mexico, in 1887, by the intrepid and prolific plant collector Edward Palmer (See Desert Breeze, July, August, and October 2017). Further, it was not a new, unidentified species but rather a specimen of Janusia californica (Palmer specimen #263), as had been noted by Sereno Watson in an 1889 enumeration of the specimens Palmer had collected earlier that year in Mexico.

In 1943, still believing that the Palmer specimen to be a new species, the French botanist Jean Arènes, decided to treat Cottsia as a synonym of Janusia, and thus Cottsia scandens became Janusia scandens. In 2007, botanists William Anderson and Charles Davis finally clarified that Arènes’s Janusia scandens was in fact Janusia californica. But they also went further and determined that the three North American species of Janusia were distinct from the South American species of Janusia. So the genus Cottsia was resurrected and used to name these three species: Cottsia californica, Cottsia gracilis, and Cottsia linearis. Never let a good anagram go to waste. — Cindy Hartwell

An abbreviated version of this article appeared in the March 2018 issue of the Desert Breeze, the monthly newsletter of the Tucson Cactus and Succulent Society.