Thursday, March 13, 2014

Semaphore Cactus - Opuntia corallicola

Semaphore cactus (Opuntia corallicola) is a very rare endemic species that is naturally found only on two islands in the Florida Keys; the largest population being located within Biscayne National Park. It is listed as a state endangered species. Though more than 500 plants should be considered safe as they are located within protected areas, this cactus, and other similar species, are threatened by an introduced moth that lays eggs inside the stems. The larvae of this moth burrow throughout the plant as they mature, and often kill the host by the damage they cause.  Its future seems to lie with the concerted conservation efforts underway to put specimens in areas protected from the moth.  This plant was photographed at the Naples Botanical Garden.
Semaphore cactus occurs in open areas within tropical hammocks of the Florida Keys.  It is erect and can reach mature heights of six feet.  The plants assume an irregular form as the pads (cladophylls) align themselves mostly on one plane. Each is oblong in shape and nearly one foot long when mature.  Like other members of this genus, they are covered by stout spines.
Flowering occurs throughout the year. They are a bright orange in color with contrasting yellow stamens. Each bloom is about 1/2 inch long.  The pollination of this plant is unknown and fruit have not been seen. Currently, reproduction is known only by asexual means - the pads break off, root, and form new plants.
Semaphore cactus is both beautiful and interesting, but its future is imperiled.  Hopefully, conservation efforts currently underway will be successful and this species will continue on into the future.


  1. What a beautiful plant. If anyone has some, I'll happily volunteer to keep some growing and moth-safe.

  2. I recently happened to find a great collection of semaphore cactus at the home of a Florida Fish and Wildlife officer who was tasked with finding a suitable habitat for the young plants. He stated that the cacti he had in his possession were 2/3 of the world's population. More images and a quick story can be found at my blog: Christopher Smart Dive Art.
    If you would like link to the images from my blog here, please credit the photos and feel free to do so!

  3. Very cool........ Thanks for sharing that story.


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