Gonolobus (2015)

By Eric Driskill (November 2015)

Gonolobus is a New World genus in the Asclepiadaceae family that comprises 129 to 150 species, with some sources listing over 300 species. It is nice to run across a genus that caters to both lumpers and splitters. For that matter, you can also find this plant sold as Matelea cyclophylla.

The genus Gonolobus was erected by Andre Michaux, a French botanist, in 1803. One of Michaux’s contributions was Flora Boreali-Americana, (The Flora of North America), which served as a botanical reference well into the 19th century.

Plants in the genus are native to South America, Central America, Mexico, the West Indies and the southern United States. Although we may recognize any old succulent Asclepiadaceae, most often you will only see Gonolobus cyclophylla offered.

In our hobby, our bias toward this one species is certainly unwarranted, if unusual flowers are something we enjoy. Fitting within the family Asclepiadaceae should be enough to spark images of otherworldly flowers of all shapes and sizes, and in colors that would make South American birds envious.

Certainly G. cyclophylla has flowers that are more unique and striking than most people will find in their yards. The 1-inch-diameter flowers are very intricate and could be compared to a chevron, a Venetian glass bead.

The leaves of G. cyclophylla appear on a deciduous caudiciform vine that can grow to at least 4 inches wide and 6 inches long, when planted in the ground and watered sufficiently during the growing season.

As attractive as the flowers may be, the deeply grooved, corky caudex is what causes many collectors to add this plant to their wish lists. The caudex certainly couldn’t be accused of rapid growth, although over time, it can grow to 8 inches wide. The caudex might remind you of several Dioscoria species, with the grooves lacking the geometric patterns found in dioscorias. The grooves do deepen over time as the caudex develops.

Another difference is the density of the bark on the caudex. Gololobus are covered in a bark with the consistency of balsa wood.

The plants can be grown in full sun, and the vining growth should be allowed to shade the caudex. Water regularly during the growing season, but water very little during the several months of its dormancy. Gololobus plants are propagated by seed.