Plant of the Week 09/10/2007: Blue porterweed (Stachytarpheta jamaicensis)

Plant of the Week 09/10/2007

Blue porterweed (Stachytarpheta jamaicensis)

Stachytarpheta jamaicensis (L.) Vahl

Photographed by: Chelsie Vandaveer
Credits: Blue porterweed photographed at the Florida Botanical Garden.
Other Information: Olympus C-8080wz

In his original description of the blue porterweed or joee, Linnaeus named it Verbena jamaicensis, and added the note, “Habitat in Jamaica and Caribaeis.” (Species Plantarum, 1753) The plant is widespread in South Florida and considered native. But there are those who think blue porterweed may have only arrived with settlers from Jamaica in the late 1700s. In the early 1800s, Martin Hendriksen Vahl re-examined the ‘verbenas’, separating out the spiked species into Stachytarpheta.

Plants sold in most nurseries are not blue porterweed, but rather the tall (to 1.2 meters or 4 feet) and somewhat rank growing nettleleaf velvetberry Stachytarpheta cayennensis (S. urticifolia) from Asia. In Florida, the nettleleaf is a pest plant often escaping from cultivation.

Our true blue porterweed (Stachytarpheta jamaicensis (L.) Vahl) is low growing, a sub-shrub only a foot or two tall. The branches spread along the ground forming a neat, dense mound. The inflorescence, a terminal spike, holds the tiny blue flowers above the bed of leaves. Each flower lasts only a day, but the spike can produce flowers for weeks. Porterweed is the larval host for the tropical buckeye, but it is best known as a nectar plant, a veritable butterfly bar, and a must for butterfly gardens.

The 60-plus species of porterweeds are part of the Verbenaceae, the verbena family. The genus is mostly native to the New World with two species of Old World origin. The common name, porterweed, started in Panama and once referred only to our little blue. The tea made from the plant was considered medicinal, good to rid the body of intestinal parasites. The tea has foam on the surface reminding people of porter ale.

(Compiled from: “Medicinal Plants of Jamaica”, Part II, G.F. Asprey and Phyllis Thornton, West Indian Medical Journal, Vol. 3, No. 1; “The So-Called Porterweeds”, Roger Hammer, The Tillandsia, newsletter of the Miami-Dade Chapter of the Florida Native Plant Society, Jul-Aug 1994; “Stachytarpheta”, Wunderlin, R. P., and B. F. Hansen. 2004. Atlas of Florida Vascular Plants . [S. M. Landry and K. N. Campbell (application development), Florida Center for Community Design and Research.] Institute for Systematic Botany, University of South Florida, Tampa)