Why does vetiver grass survive water logging?

Root cross section showing large aerenchyma.

I am often asked how vetiver can survive water logging.  This unique plant has special cells in its leaves and roots that allow it to adapt to water logged conditions.  In effect it is able to move oxygen from its leaves to its roots and does not suffer from hypoxia (oxygen starvation).  Some excellent research by P. Khnema and S.Thammathaworn of Thailand see: Leaf Anatomy of Vetiver Grass Supporting the Potentially C Sequestration (2011) explains the process and shows in detail the cells that are able to achieve this.  They produced a nice powerpoint with many of the details. There is a fascinating discussion starting on page 12.  They conclude “… Large lysigenous intercellular spaces were found in mature leaves, but very small sizes in developing leaves, which suggested relative gas circulation in roots and encouraged deeply root penetration. Consistently, I found that aerenchyma at root cortex and air cavity at pith were strong evidences of aeration system from leaves to roots. To avoid hypoxia/anoxia, large lysigenous intercellular spaces at laminas were a character of aquatic plants or long term flooding-tolerant plants by transporting O2 from leaves to roots. Moreover, I guessed atmospheric O2 could pass into vetiver via a pith cavity at culms by the theories calling “Humidity-induced convection” and “Venturi-induced convection”.  These two scientists received the coveted “King of Thailand Award” for this work – they deserved it.  Vetiver is truly a remarkable grass.

Dick Grimshaw