Tree protuberances are growths that protrude from the trunk or branches of a tree. The four crossword solutions for this term are KNAR (4 letters), GNARL (5 letters), KNUR (4 letters), and BURL (4 letters). KNAR is a term used to describe a knot or lump on the surface of a tree trunk or branch. GNARL is a term used to describe a twisted, gnarled branch or root. KNUR is a term used to describe a knot or lump on the surface of a tree trunk or branch. BURL is a term used to describe a large, rounded growth on the trunk or branch of a tree.