1) To become wood 2) To make ligneous 3) To turn into wood 
to make woody; to turn into wood
• (v. t.) To convert into wood or into a ligneous substance. • (v. i.) To become wood.
To become woody
Lig'ni·fy intransitive verb (Botany) To become wood. Lig'ni·fy (-fī) transitive verb [ imperfect & past participle Lignified (-fīd); present participle & verbal noun Lignifying (- fī`ĭng).] [ Latin lignum wood + -fy : confer French lignifier
To become woody