Porterweed

Porterweeds are a group of about 65 annual and perennial herbs and shrubs in the genus Stachytarpheta. They are well-known for their ability to attract butterflies, but some care should be taken when choosing these plants for the garden as some species have invasive tendencies. Here are the two porterweed species growing in the MOSI Outside gardens.

Jamacian Porterweed (Stachytarpheta jamaicensis) is a prostrate species that grows in low spreading mounds up to about a foot in height. Although it is considered a Florida native, Jamacian Porterweed was possibly brought over to Florida with early Bahamian settlers. Porterweeds are wonderfully attractive to butterflies as nectar plants and are an excellent addition to a butterfly garden. Jamacian Porterweed blooms throughout the year but may die back significantly during a freeze. Identify this porterweed by its flatter leaves with rounded serrations.

Blue Porterweed (Stachytarpheta cayennensis) syn (Stachytarpheta urticifolia) is an upright variety of porterweed that is also very attractive to butterflies. The plant may grow four to six feet in height and this species re-seeds readily, spreading rapidly. Blue Porterweed is a favorite of the Long Tailed Skipper butterfly which can often be found buzzing this plant in numbers. This variety is native to tropical areas of Asia and forms a woody shrub. This non-native variety has become a problem in some areas of Florida and has been listed as a Category II invasive species by the Florida Exotic Pest Plant Council. Identify this species as non-native by its height and deeply quilted leaves with sharply serrated edges.

Compare the two leaves: Invasive S. urticifolia on the left; Florida-Friendly S. jamaicensis on the right.

 What's In a Name? The genus name derives from the Greek stachys (spike) and tarphys (thick) which refers to the thick flower spikes that produce blooms on these plants. Porterweeds are used as a medicinal plant in the Caribbean and one particular species is used to make a foaming brew that is used to reduce fevers.