Porterweed

Stachytarpheta jamaicensis (L.) Vahl

Stachytarpheta mutabilis (Jacq.) Vahl.

Stachytarpheta urticifolia Sims

stake-kee-TAR-feh-tuh, jah-may-SEN-sis, mew-TAB-uhl-iss, ur-tis-ah-FOAL-ee-ah

Verbenaceae

 Explanation of name: Stachytarpheta: flowers on spike, jamaicensis: from Jamaica, mutabilis: changeable, urticifolia: with leaves resembling Urtica (nettles)

Natural range: S. jamaicensis native to Florida. S. urticifolia native to the Old World tropics (WU1). S. mutabilis native to American Tropics (not Florida (LLA).

Recognition: All species have flowers on spikes. Stachytarpheta jamaicensis is the smallest of these three species, up to 2(4) feet tall with light violet flowers on spikes about 6-8" long. It is a low sprawling shrub with leaf teeth obtuse. Stachytarpheta urticifolia has purple/blue flowers and grows to 4' tall with 1' flower spikes. The leaf teeth are acute. Stachytarpheta mutabilis grows up to 6' tall with flower spikes up to 1.5' long. The flowers are pink or purple.

Key to Species of Stachytarpheta Cultivated in South Florida

(some data from WU1)

See also: http://www.afnn.org/upload/pdf_forms/article3porterweed.pdf

1. Corolla usually reddish or pink (or rarely blue), 13-18 mm long; plants to 6’ tall or taller…S. mutabilis

1. Corolla usually blue or violet, shorter than 13 mm; plants usually under 4’ tall…2

2. Teeth on leaf blades obtuse (blunt); plants sprawling to upright; floral bracts ovate-lanceolate…S. jamaicensis

2. Teeth of leaf blades sharp-tipped (acute, acuminate); plants upright; floral bracts lanceolate-subulate…S. urticifolia

 Landscape uses: Tough, easily grown, easily propagated, undemanding edge, border, or massing plants. A little weedy. Stachytarpheta mutabilis has the showiest flowers. Stachytarpheta jamaicensis is a must for butterfly gardens and for xeriscaping but is not showy. Drought tolerant. Because the other two species are alien and are prone to escape cultivation, only S. jamaicensis is recommended for Florida.  Stachytarpheta urticifolia escapes cultivation in South Florida (WU1). Stachytarpheta mutabilis has escaped elsewhere. (http://www.hear.org/pier/species/stachytarpheta_mutabilis.htm).

Note: UFFPS559 contradicts more current sources on key points and may represent confusion among species.  LLA notes that the species hybridize.