Definitions for calloseˈkæl oʊs
Random House Webster's College Dictionary
having thickened or hardened spots, as a leaf.
Ref: callus (def. 2). 2
Origin of callose:
1860–65; < L callōsus
A plant polysaccharide comprising glucose residues linked together through u03B2-1,3-linkages, produced chiefly in response to wounding and infection.
furnished with protuberant or hardened spots