From
http://www.totse.com/en/drugs/rare_and_exotic_drugs/add.html
:
Arundo donax (aka "Giant Reed")
Yes. It contains some DMT, but not very much. Someone told me the other day that a friend of theirs that is investigating this (solicited samples from interested parties, and used thin layer chromatography to assay the root stocks, from what I was told) says there's "little or no DMT" in Arundo donax rhizomes.
The paper that first found DMT and a few other indole alkaloids in Arundo donax (Ghosal) working in India (River Reed is used in Ayurvedic medicine)
also found only trace amounts. You'd have to extract several kilograms to get a psychoactive dose of DMT. There are also several cardioactive glycosides and other substances that would produce annoying side effects if a crude extract were consumed - the effect of Arundo donax extract on heart muscle (another paper by Ghosal et. al.) gave me the impression
that crude Arundo extracts are potentially dangerous. You'd have to resort to solvent extraction followed by column chromatography to extract pure DMT from the roots - a process probably requiring several liters of solvent just to produce one dose of DMT.