Sentence:  Swadesh , and therefore Hoijer , felt compelled to omit all terms denoting species or even genera ( fox , vulture , salmon , yellow pine , manzanita ) ; their classes of animal and plant terms are restricted to generalizations or recurrent parts ( fish , bird , tree , grass , horn , tail , bark , <WSD>root</WSD> ) . 
Meaning of the word marked with <WSD> tags:  (botany) the usually underground organ that lacks buds or leaves or nodes; absorbs water and mineral salts; usually it anchors the plant to the ground