You may enlarge any of the images in this blog by clicking on it.  Click again for a full screen image.

Ocotillo is one of the weirder plants growing in the southwestern desert.  It has few relatives (the even weirder Boojum Tree that grows in Baja, Mexico is one of them).  It looks odd and its behavior may seem  even odder.

These plants have no central stems.  Rather, an Ocotillo will send up a cluster of woody stalks that are about 1 1/2 inches thick and that rise about 10-15 feet from their bases to their tips.  The stems are covered with extremely sharp thorns that are about 1/2 inch long.  The plants rarely have leaves.  Most of the year all one sees is the bare stalks.  However, when it rains, the Ocotillo are stimulated to put out leaves.  The leaves are oval in shape, about an inch long, and cover the plants from their bases to the tips of their stalks.  A couple of weeks of dry weather will cause the leaves to shrivel, turn brown, and fall off, leaving the stalks bare until the next rainy spell.  An Ocotillo is as likely to put out new leaves in December as it is in July.  It all depends on rainfall.

Ocotillos ordinarily bloom once a year and most of them bloom in late March/early April.  The plants put out a bract of brilliant orange-red flowers at the tip of each stem.  From a distance these flower bracts are so bright that one can see them even if the rest of the plant is almost invisible.  Hummingbirds are huge fans of Ocotillo flowers.

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Ocotillos are a relatively common sight in our local desert but these plants definitely have habitat preferences.  They love limestone and one often sees them covering hillsides where limestone is prevalent.  And, that brings up something interesting.  Limestone is the stuff that caves and caverns are made of.  Consequently, an Ocotillo-covered hillside may signify that there’s a cave down below.  Cavers are aware of this and they deliberately search Ocotillo-covered slopes for possible cave openings.  Karchner Caverns, a gigantic cave complex southeast of Tucson is just such a place.  The opening to the caverns was discovered a few decades ago by cavers who were deliberately searching areas where lots of Ocotillo grew.

Image made with a Canon 5DS-R, 180 f3.5L Macro Lens, aperture priority setting, ISO 160, f6.3 @ 1/160.


One response to “Ocotillo”

  1. tkiiatmindspringcom says :

    These are certainly a brilliant color! And interesting information about the limestone/cave connection.

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