Dive summary:

• German scientists looking for environmentally friendly building materials are enthusiastic about plain old swamp cattails as material to fill out insulating panels for buildings.
• According to researchers at the Fraunhofer Institute for Building Physics, a construction-materials think tank, the structure of cattail leaves with fibers and a sponge-like material has great insulating properties, and the plants are naturally mold resistant because they grow in wet environments.
• The head of the institute's test center, Dr. Martin Krus, has a patent pending for an insulation panel that uses magnesite as a binding material and was developed with an industrial partner.

From the article:

It delivers excellent fireproofing, soundproofing and heat insulation, and is relatively permeable, but sufficiently tight so that, with most applications, one can dispense with a vapor control barrier. ...