1.

    T-------T 
   / \     / 
  /   \   /
 /     \ /
T-------T-------T       T
 \     / \     / \     / \
  \   /   \   /   \   /   \
   \ /     \ /     \ /     \
    T       T-------T------T
                   / \    /
                  /   \  /
                 /     \/
                T------T
You need to be quick when removing thorns.

First remove the eight thorns in the middle and the bottom right one. Then remove the two triangles in the middle.

    T-------T 
   / \     / 
  /   \   /
 /     \ /
T-------T               T
 \     /               / \
  \   /               /   \
   \ /               /     \
    T               T------T
                   / \    /
                  /   \  /
                 /     \/
                T------T

Wait for the thorns to grow back then remove the 6 in the middle and all the ones from any side with the three triangles. Remove those same three triangles. Wait for them to grow back then rmove all the thorns and triangles