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ABSTRACT:

Hydraulic architecture of Monstera acuminata: evolutionary consequences of the hemiepiphytic growth form

Journal Article

Lopez-Portillo J; Ewers F; Angeles G; Fisher J

‚Äč

2000

New Phytologist

145

289-299

The hydraulic architecture of the secondary hemiepiphyte Monstera acuminata was examined in native plants from Los Tuxtlas Veracruz Mexico to determine how it compared to better-known growth forms such as trees shrubs lianas and primary hemiepiphytes. Monstera acuminata starts its life cycle as a prostrate herb. As it ascends a tree or other vertical support the stem becomes thicker produces larger leaves and may die back from the base upwards until only aerial feeding roots serve to connect the stem to the soil. Unlike the pattern of vessel-size distribution along the stems of woody dicotyledons M. acuminata has its wider vessels at the top of the stem decreasing in diameter towards the base. Also peculiar is the fact that Huber values (axis area/distal leaf area) tend to increase exponentially at higher positions within the plant. Based on the hydraulic conductivity (k(h)) and leaf-specific conductivity (LSC K-h/distal leaf area) the base of the stem potentially acts as a severe hydraulic constriction. This constriction is apparently not limiting as aerial roots are produced further up the stem. The plants have remarkably strong root pressures up to 225 kPa which may contribute to the maintenance of functional vessels by refilling them at night or during periods of very high atmospheric humidity as in foggy weather and rain. In common with dicotyledonous plants vessel length vessel diameter k(h) specific conductivity (k(s) k(h)/axis area) and LSCs were all positively correlated with axis diameter. The features of the hydraulic architecture of M. acuminata may be an evolutionary consequence of an anatomical constraint (lack of vascular cambium and therefore of secondary growth) and the special requirements of the hemiepiphytic growth form. pipe model

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The Liana Ecology Project is supported by Marquette University and funded in part by the National Science Foundation.