Monday, July 2, 2012

Born in the U.S.A.: Barbed-wire cactus, Acanthocereus tetragonus


What could be more all-American than native plants? In honor of Independence Day,
we'll be featuring species with red, white, or blue flowers or fruit this week, so stay tuned!



Figure 1. Upright growth habit of A. tetragonus,
with closed flower. Photo credit: Alan Boatman.

By Daneisha Hawkins

This post is one of a series from professor Nisse Goldberg's Plant Taxonomy students at Jacksonville University.

Classification
Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Order: Caryophyllales
Family: Cactaceae
Genus: Acanthocereus
Specific epithet: tetragonus
 
Figure 2. Night-blooming A. tetragonus shows
its white tepals with yellow stamens.
Photo credit: Bob Upcavage.

Description
Barbed-wire cactus, or Acanthocereus tetragonus, is typically found along the coast from St. Lucie County southward to Lee County, including the Keys. Interestingly, the plant is not vouchered in Broward County. Of the 12 native cactus species in Florida, only two are listed as threatened - A. tetragonus is one of them. This plant is found growing in sandy, coastal hammocks.

Figure 3. Shiny berry of the barbed-wire cactus.
Photo credit: Shirley Denton.
The barbed-wire cactus gets its name from its dangerous-looking white to gray spines (Figure 1). Despite their ominous appearance, the spines do not deter the endangered Key Largo woodrat from eating the plant's stems. Individuals usually grow upright or on other plants (Figure 1). The flowers have white tepals that open around midnight and close at dawn (Figure 2). In those few hours, pollinators such as the hummingbird moth (Hemaris spp.) visit the fragrant flowers for their nectar. The berries are red, shiny, and sweet (Figure 3).


Where can you see one in the wild? Visit Everglades National Park and Biscayne National Park.

References
Image sources
Figure 1. http://florida.plantatlas.usf.edu/Photo.aspx?id=13328
Figure 2. http://florida.plantatlas.usf.edu/Photo.aspx?id=5732
Figure 3. http://florida.plantatlas.usf.edu/Photo.aspx?id=5730

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