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Stachytarpheta jamaicensis (L.) Vahl 1804
pronounced: stay-key-tar-FEE-tuh juh-may-KEN-siss
(Verbenaceae — the lantana family)
common names: Snakeweed, Blue Porterweed, Jamaica Vervain, Blue Snakeweed
People who think that we are short of wildflowers here would do well to walk some of our bush tracks after the first heavy rains of the summer are followed by sunshine. There is an amazing variety of wildflowers, and this plant, to me, is one of the most attractive, especially where it grows in fairly large patches. It is, of course, not a native, but comes from tropical America, and the purists will hate me for liking it!
This pretty low-growing plant has colonized many of our roadsides and bush tracks, and is something of an invasive species, but I can think of worse species by which to be invaded! It blooms for much of the year, except in the driest periods, with dainty blue flowers that grow on a long, thick spike, making it an excellent nectar plant for butterflies. It also attracts humming birds. Although the plant can tolerate some salt spray, it does not do well right on the beach. It also dislikes areas of standing water, and is more prolific on the hilly slopes than on the flat land in the various bays.
Blue porterweed is a low, usually spreading annual or perennial herb, 60–120 cm tall, sometimes somewhat woody towards the base, and often purplish throughout. It has a long tap root. The stems branch dichotomously, are sparsely pubescent or glabrous, the nodes being usually sparsely pilose.d
The leaves are often bluish or greyish when fresh, alternate or opposite, somewhat fleshy, elliptic to ovate, up to about 10 cm long and 4 cm wide, though usually smaller than that. The upper surface is smooth, the lower surface less so; the margins are serrate, with teeth angled forward, and the petioles anything up to 3 cm long.
The calyx is completely embedded in rachis furrows, somewhat compressed, about 5 mm long. The corolla is blue to purple with a white throat, about 1 cm long. Only a few flowers on each stalk are open at any time.
This plant is cultivated in many places as attractive ground cover. It will grow on a very wide variety of soils, including those poor in nutrients, and is a fast grower. It prefers full sun.
Photographs taken in Picnic Bay 2009
Page last updated 18th February 2017