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Leaf Production Can Be Decoupled from Root Activity in the Desert Shrub Ocotillo (Fouquieria splendens Engelm.)
Keith T. Killingbeck
The American Midland Naturalist
Vol. 124, No. 1 (Jul., 1990), pp. 124-129
Published by: The University of Notre Dame
Stable URL: http://www.jstor.org/stable/2426085
Page Count: 6
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Glasshouse studies using severed ocotillo (Fouquieria splendens) stem segments were initiated to measure the capacity of these stems to produce leaves when decoupled from concurrent root activity. Rootless stem segments began to produce leaves within 24-48 h after they were supplied with water. Foliation was supported solely by external addition of distilled water and internal mobilization of stem nutrients. Roots were never produced on any of the stem segments during the entire 1070 stem-days of experimentation. Rootless stem segments that were defoliated five times still produced leaves at 90% of their nodes. The ability of rootless ocotillo stems to repeatedly produce new cohorts of leaves without the addition of exogenous nutrients or hormones appears to be unprecedented. The possible adaptive significance of decoupling leaf growth from concurrent root activity is discussed.
The American Midland Naturalist © 1990 The University of Notre Dame