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Unusual Water Relations in the CAM Atmospheric Epiphyte Tillandsia Usneoides L. (Bromeliaceae)
Martin, Craig E. Schmitt, Andreas K.
Martin, Craig E.
Schmitt, Andreas K.
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Abstract
Past studies have reported two unusual aspects of the water relations of the atmospheric CAM epiphyte
Tillandsia usneoides L. (Bromeliaceae): a drought stimulation of nocturnal C02 uptake, and nocturnal absorption
of water vapor. Contrary to past reports, a 10-d drought did not stimulate nocturnal C02 uptake
in this species. On the other hand, previous reports of nocturnal water vapor absorption were confirmed in
situ throughout a year, although tissue hydration from this source was insufficient to offset daytime water
loss. Deposition of dew on the plants was never observed in the field. It is hypothesized that the unusual
nature of the water relations of T. usneoides is attributable to the interactions between two "pools" of water
and the external atmosphere. The dense indumentum of trichomes obscuring the surface of this epiphyte
comprises one pool and is most likely responsible for rapid hydration early in the night and dehydration
early in the day. In addition, stomata control water loss from the living mesophyll cells, the second pool,
for the remainder of the night. The high rates of water loss observed throughout the day when stomata are
closed probably result from leakage through the trichomes.
Description
This is the publisher's version, also available electronically from: http://www.jstor.org/stable/2995179.
Date
1989
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The University of Chicago
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Citation
Martin, C.E. and A.K. Schmitt. 1989. Unusual water relations in the CAM atmospheric epiphyte Tillandsia usneoides L. (Bromeliaceae). Bot. Gaz. 150: 1-8.