adjective

knobbly, rough, and twisted, especially with age.

the gnarled old oak tree

knobbly,knotty,knotted,gnarly,lumpy,bumpy,nodular,rough,twisted,bent,crooked,distorted,contorted,knurled,nodulous,nodose,arthritic,misshapen,leathery,weather-beaten,weathered,wrinkled,wizened,thrawn,wry