(i) Tree

(ii) Ets (6086) - a tree (from its firmness); hence, wood (plural sticks):

From a primitive root; properly, to fasten (or make firm), i.e. to close (the eyes):

(iii) The righteous as strong and with deep spiritual roots.

(iv) (a) 2:3; 4:14; 7:7,8; 8:5

(b) Jer 17:7-8 ; Isa 61:3