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

Abstract

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 leafspecific 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.

A global analysis of xylem vessel length in woody plants

“…We found evidence that both vessel length and vessel diameter increased as the diameter of sampled stems increased. This is consistent with what has been reported in previous studies that found that vessel length ( Zimmermann and Jeje, 1981 ;Zimmermann and Potter, 1982 ;Ewers et al, 1990 ;Ewers and Fisher, 1989b ) and vessel diameter ( Zimmermann and Potter, 1982 ;Ewers andFisher, 1989b , Ewers et al, 1990 ;Sperry and Ikeda, 1997 ;López-Portillo et al, 2000 ;McCulloh et al, 2010 ) increased with plant age and/or stem size.…”

Size‐correlated morpho‐physiology of the aroid vine Rhodospatha oblongata along a vertical gradient in a Brazilian rain forest

“…Both patterns are also cited for the aroid vine Monstera acuminata C. Koch (López‐Portillo et al . ). This stem structure could only be mechanically sustained if anchor roots are attached to the host trunk.…”

“…The internode measurements were subsequently extrapolated to the transverse section following López‐Portillo et al . ().…”

“…For aroid vines, only López‐Portillo et al . () have evaluated the hydraulic architecture of four individuals of the aroid Monstera acuminata C. Koch., which increases in size, but they did not establish a clear allometric correlation between size and morpho‐physiology of leaves, shoot and aerial roots.…”

Living with Limited Water: I. Shoot Hydraulic Resistance as Water-Saving Strategy and its Significance in Varietal Improvement of Rice

“…The same was shown by many studies at the whole-plant level, especially short-term ones involving pot-grown plants or seedlings. Thus, there seems to be consensus that like most of shallow-rooted agricultural crops, the hydraulic limitation is an important factor for tall and deep-rooted plant evolution as well (Lopez-Portillo et al 2000;Mencuccini 2003). Comparison of actual patterns of vessel branching of plants with models of vasculature proposed for plants show conflicting evolutionary pressures not only for water transport efficiency versus safety but also for mechanical strength (Niklas 1992;McCulloh and Sperry 2005).…”