CHARRED WOOD STIMULATED GERMINATION OF TWO FIRE‐FOLLOWING HERBS OF THE CALIFORNIA CHAPARRAL AND THE ROLE OF HEMICELLULOSE

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Abstract
Germination of the fire‐following chaparral herbs, Emmenanthe penduliflora (Hydrophyllaceae) and Eriophyllum confertiflorum (Asteraceae), previously has been shown to be stimulated by charred wood from the widespread chaparral shrub Adenostoma fasciculatum (Rosaceae). A series of investigations undertaken to clarify this effect gave the following results. Light is not required, but may enhance the response. The effect is not limited to A. fasciculatum but is produced by a wide variety of chaparral and non‐chaparral woods. Charring is not necessary; wood heated to 175 C for 30 min produced the same germination stimulation. The stimulatory compound is water soluble, effective within 24 hr exposure and active at 0.04 g/50 cc soil. Germination was stimulated by heated xylan, a hemicellulose, and by heated glucuronic acid, a common side chain of xylan and other hemicelluloses. Heating produced changes in the color and consistency of xylan and glucuronic acid. An oligosaccharin‐type molecule is postulated to be produced by heating xylan or other hemicelluloses with glucuronic acid side chains. Previously described oligosaccharins are derived from galactouronic acid and xyloglucan which are structurally and functionally related to compounds tested here.
Funding Information
  • Faculty Research Grants from Whittier College