Outside the West Texas town of Valentine, botanical scientists fell in love with a new plant species.
OK, the alliteration loses much in the adaptation, and my apologies to Marty Robbins, but a University of Utah release reports that amateur collectors actually found the first two specimens of a prickly plant in west Texas in 1974 and 1990 respectively. But for two decades, the 14-inch-tall plant was serially misidentified as being a member of one species, then another and then a third.
However, a long and painstaking search effort has finally turned up a third spiny plant specimen that University of Utah botanist Lynn Bohs and her researcher colleagues have identified the as a new, possibly endangered species, and named it “from the heart” in Latin because it was found in Valentine, Texas, (population 134) in 2010.
Most new plant species are found in the tropics, and it is uncommon for a new one especially a flowering plant to be found in the United States, explains Dr. Bohs, who is senior author of a new study published in the August 1, 2014 issue of the Journal of the Botanical Research Institute of Texas (BRIT) in which Solanum cordicitum (pronounced So-lay-num core-duh-SEE-tum) is described and named.
“It’s a new, unique plant from the United States, Dr. Bohs says. “Plus its from Valentine, which is extremely charming, and that gave rise to its name, S. cordicitum.” Cordicitum is derived from cordicitus, Latin for from the heart, but is altered to cordicitum because it must end with the same syllable as Solanum to comply with naming rules. The plant has no common name. The derivation of Solanum is unknown, but may be from sol for sun or from solamen for consolation, comforting or quieting.
Some of the Solanaceae family, including the genus Solanum, known as the nightshade family, are literally and permanently quieting because they are deadly poisonous, notes Dr. Bohs, and many of the plants are toxic, hallucinogenic or medicinal, although three economically important, global food crops: tomatoes, potatoes and eggplant (the most closely related to S. cordicitum, Dr. Bohs says), as well as chili peppers, are edible. However, most of the genus, one of Earth’s largest genera of flowering plants numbering some 1,500 species, including the nightshades, are poisonous.
The Solanaceae Source, which aims to provide a worldwide taxonomic monograph of the nightshade family, Solanaceae, notes that in addition to the handfull of species used as food (potatoes, tomatoes, eggplant, chili peppers, and and “a host of minor fruit crops”), some are also used medicinally such as deadly nightshade, jimson weed, tobacco, and henbane which are sources of drugs such as atropine, hyoscine, nicotine and other alkaloids. Species such as tomato, potato, tobacco, and petunia are also important experimental organisms in genetics and molecular biology, and Solanaceae species of ornamental or decorative horticultural importance include petunia, Salpiglossis (commonly known as painted or velvet tongue), and Schizanthus (commonly known as butterfly flower), Browallia and floripondio.
Dr. Lynn Bohs’ research interests include plant systematics and phylogeny and the evolution of domesticated plants, with her main focus the taxonomy and evolutionary relationships of plants in the Solanaceae family, including lesser-known species with potential uses as foods or medicines. She notes that some solanaceous plants have been subjected to intensive human selection and several are known only in cultivation, allowing their use as systems to study the evolutionary interface between plants and people.
Presently, the Bohs Laboratory is concentrating on the systematic and evolutionary relationships in Solanum, the largest genus in the family. Ongoing projects include construction of an overall phylogeny for Solanum and related genera using molecular and morphological characters and more detailed studies of several subgroups within the genus, some of which contain economically useful species.
One example of a focused study concerns the putative domesticate Solanum betaceum, the tree tomato. This species is widely grown throughout the tropics and subtropics for its edible fruits. Until recently, it was considered to be known only form cultivation and its wild relatives and place of origin were unknown. Using a variety of approaches, including morphology, biosystematics, molecular techniques, and field work, Dr. Bohs and her team have been able to identify the closest relatives of S. betaceum and locate wild populations of this species in Bolivia and Argentina. The same array of approaches can be used to investigate the origin and evolution of plant domesticates in the Solanaceae and in other plant families.
Photo Caption: Botanist Lynn Bohs, a University of Utah biology professor shown here in a campus greenhouse, has published a new study that identifies a new and prickly species named Solanum cordicitum (not shown in photo). The word cordicitum is derived from Latin for “from the heart” because two of the three known specimens of the possibly endangered plant were found in the tiny west Texas town of Valentine.
Photo Credit: Lee J. Siegel, University of Utah
The BRIT journal report titled “New Species And Combinations In Solanum Section Androceras (Solanacae)”, is coauthored by Dr. Bohs with Stephen R Stern – an Assistant Professor in the Department of Biological Sciences at Colorado Mesa University in Grand Junction, CO; and Jeffrey Keeling, who made the latest S. cordicitum specimen discovery while doing research for his master’s degree in the Department of Biology at Sul Ross State University in Alpine, Texas, which is located about 60 miles southeast of Valentine. Mr. Keeling, MS, Biology, was among 214 students, 142 from the Alpine Campus and 72 from Rio Grande College, who received degrees during spring commencement exercises at Sul Ross State University on May, 16.
The UU release reports that the three S. cordicitum specimens — the only ones known to exist — are all now pressed and mounted in museums. Jeffrey Keeling collected the specimen of S. cordicitum he found in 2010, pressed and mounted it, then sent it to Dr. Stern in Grand Junction. The specimen found in 1974 now is at the University of Texas at El Paso. The 1990 specimen is stored at the University of Texas at Austin.
The International Union for the Conservation of Nature’s Red List of endangered and threatened species categorizes the status of newly identified S. cordicitum as data deficient, but Dr. Bohs says it probably is really endangered.
Stalking A Suspected New And Endangered Species
The newly identified S. cordicitum grows only about 14 inches tall. Its stems and leaf stalks have very short hairs as well as prickles or spines about one-fifth-inch long, but that’s still long enough to stick you, Bohs warns. The leaves have three or four lobes on each side. Prickles also cover the flower clusters, which have five to eight flowers.
The first specimen of S. cordicitum was collected in October 1974 on U.S. 166 about 30 miles west of Fort Davis, Texas. The second was discovered in September 1990, when Valentine resident Howard Elder found the plant on his property. A botanist wrongly identified the plant as S. heterodoxum. It later was wrongly re-identified two more times: as S. davisense in 1997 and as a variety of S. grayi in 2006.
However, Dr. Bohs and her researcher colleagues believed the specimen was none of those species, because its flower petals are white instead of yellow, and its flower stalks are longer and flowers are larger than closely related species. There also are differences from other species in leaf shape and in stem hairs.
Also, a study published in 2010 by Drs. Stern, Bohs and Utah postdoctoral researcher Terri Weese showed the plant’s DNA differed from known species. And the plant is an annual, while related species are perennials.
Consequently, Dr. Bohs and her collaborators decided to try to find more specimens, with Stephen Stern — then a Utah grad student — spending days looking for the plant in Texas without success.
In November 2013, Jeffrey Keeling searched the Valentine area for days before finding the third specimen on the Elder property near where the 1990 specimen was recovered.
“He looked everywhere and finally found one horrible, wilted plant specimen,” says Dr. Bohs. “It looked awful. It was wilted and brown and had some seeds we thought wed be able to germinate, but they weren’t any good. It was totally pathetic, and we were sad because we wanted a beautiful picture of the flowers to put in a publication.”
“It’s probably not extinct because Keeling found one plant that had been living in 2013,” Dr. Bohs observes. “Whether that was the last one or not, we don’t know. Were hoping that by publicizing this, more people will look for it and more plants will be found.”
Dr. Stern believes more are out there, noting that for the past 3 years in the Bohs Lab he has have been working on the taxonomy and phylogenetics of the genus Solanum through a variety of projects. These include creating phylogenies for the Geminata clade and the Old World spiny Solanum clade, revising section Gonatotrichum, and his PhD project, which is focused on section Micracantha.
Three Other Plants Elevated from Varieties to Species
Discovery of the new S. cordicitum species was a small part of a five-year project of Dr. Bohs to more accurately classify and create a comprehensive online inventory of all 1,500 Solanum species.
In the same study, the botanists elevate to full species status three other closely related plants that were previously named varieties of other Solanum species but that DNA analysis showed to be separate species. Like the new species, they all belong to a group of Solanum named section Androceras, which now includes 16 species with the reclassifications by Dr. Bohs and her colleagues:
S. knoblochii (no-BLOCK-ee-eye) previously was classified as S. citrullifolium variety knoblochii. Only five plants have been collected from two sites in Mexico’s western Chihuahua state. Its status is data deficient, but Dr. Bohs and colleagues write that it warrants near-threatened status.
S. setigeroides (seh-tidge-ger-OID-ees) and S. novomexicanum (novo-Mexi-can-um) both were classified previously as varieties of S. heterodoxum. The first species is a widespread weed from northern Chihuahua and west Texas to central Arizona and New Mexico. The other is found only in northern New Mexico. The Red List categorizes both as species of least concern, meaning they are neither threatened nor endangered.
Weedy But Not A Weed
S. cordicitum and the varieties that are newly elevated to species belong to section Androceras, which is a group of weedy Solanum plants native to the central and southwestern U.S. and Mexico. That is unusual because most Solanum groups are tropical, Dr. Bohs says. The most widespread Androceras species is S. rostratum, known as buffalo bur, prickly nightshade and Kansas thistle.
In all Androceras species, the calyx, or outer envelope of the flower and fruit is really spiny, Dr. Bohs explains. A larger group of 350 to 400 Solanum species are known as spiny solanums because they have prickles. The group includes wild eggplant. Spines have been bred out of domestic eggplant.
While S. cordicitum belongs to a weedy group within the spiny solanums, technically it isn’t a weed because weeds are more common and spread easily, Dr. Bohs says.
In addition to phylogenetic research, Dr. Bohs is also involved in floristic and revisionary studies. Current floristic projects at the Bohs Lab include treatments of the Solanaceae for Costa Rica, Solanum for North America, and selected solanaceous taxa for Mesoamerica.
Like other plants in Androceras, the new S. cordicitum species and its five-petaled flowers are bilaterally symmetrical (like a mirror image down a vertical line) but not symmetrical in all directions because the five petals vary in size. Four of its yellow anthers pollen organs within the flower are the same size, but the fifth is bigger, Dr. Bohs noting that “Its got a beautiful, interesting flower form unique in Solanum.”
University of Utah
Sul Ross State University
Colorado Mesa University
Journal of the Botanical Research Institute of Texas (BRIT)
University of Utah
Lee J. Siegel, University of Utah
Jeffrey Keeling, Sul Ross State University
University of Texas Herbarium