Vestured pits: Do they promote safer water transport?

摘要

The distribution of vestured pits in angiosperms is briefly reviewed. In some major clades, the character is of constant occurrence and thus very conservative; in others, it is more variable and apparently subject to both parallel origins and reversible losses. There is a striking correlation between the type of vessel perforation plate and vestured pits. Virtually all taxa with vestured pits have simple perforation plates. This correlation, together with contrasting ecological trends for scalariform perforation plates and vestured pits, has inspired functional hypotheses that vestured pits contribute to hydraulic safety. Whereas scalariform perforations may be instrumental in reducing the effects of freezing-induced embolisms in temperate to boreal and alpine regions, vestured pits seem to be a good candidate to facilitate embolism reversal in xeric and warmer regions with high transpiration rates. The presence of highly lignified structures within the pit chamber may influence hydraulic resistance, decrease vulnerability to cavitation, or help to repair embolism by compartmentalizing or affecting the contact angle of the convex air-water interface within intervessel pits.