This site is no longer maintained and has been left for archival purposes

Text and links may be out of date

NURSE TREES
NURSE TREES

Saguaros and other large cacti of the Sonoran desert develop only slowly from seeds - the seedlings might take 2-3 years to reach a height of only 3 cm. During this time they are very vulnerable to drought in the intense exposure of the sun, so they almost invariably develop in the shade of a tree or shrub - a "nurse plant". For example, the image below shows a young saguaro - about 40 cm tall and probably 15 years old. It has grown up in the shade of a shrub (limber bush).

The following images show further examples of saguaros and another large cactus - the organ pipe cactus - which have developed from seedlings in the shade of shrubs or trees. These nurse plants not only provide shelter from the sun but also provide a soil with at least some organic matter (from fallen leaves etc.) and a richer supply of nitrogen - most of these nurse trees are nitrogen-fixing species, with Rhizobium or related bacteria in their root nodules.

Go to:

This site is no longer maintained and has been left for archival purposes

Text and links may be out of date