Roots on Exposed Rock Faces & Climbing Roots
Root Directory
One day I was amazed to see the root system of a plant impressed on a cliff
face above the Pali Overlook. Most of the main roots appeared to be exposed, yet it
bore a living shoot system. This is a rather moist spot that receives a lot of mist, and
this could represent an aberration, but I have since seen similar specimens in drier
areas.
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| Small Tree growing on a cliff-face above the Pali Overlook, Oahu - Note the white roots which are splayed across the sheer rock-face. | Cactus roots covering the upper part of a cliff-face. An Opuntia species is in the foreground but most of the roots are produced by a Hylocereus species in the background. |
I recently made another, related stunning observation. I am easily stunned by roots!!!! I saw that two cacti (Hylocereus sp. and Opuntia sp.) had invaded dry open sites in the leeward foothills. I was amazed to see a southeast cliff covered with roots from the cacti which were growing approximately 50 feet above the soil below the cliff. The Hylocereus species was most abundant above the cliff. These roots must have special adaptations which allow them to grow on such a dry, hot rock face. Little else, besides crustose lichens, grew on this cliff face. I also noticed that the Hylocereus used its roots to climb trees. Growth by the Hylocereus eventually engulfed small trees and killed them. This is a problem that needs further studies before more dry forest ecosystems are destroyed! Cacti are well known for the adaptations of their stems which allow them to grow in dry (xeric) environments. I do not know if anybody has investigated the anatomy and physiology of their aerial roots. This would be a good undergraduate research problem!!!
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  Hylocereus species climbing a tree. This looks innocent but sinister forces are at work!!!! |
