I just recently did the ISA CTW test and the tree id portion during the written part was very small. Photos were provided and latin names were used. I received a list of tree with both latin and common names to study from. Details of how the written portion are weighted were online.
The 'tree...
BRITISH COLUMBIA REGIONAL TREE CLIMBING COMPETITION
SATURDAY, JULY 12, 2008 – CHECK IN 7:30AM
QUEEN’S PARK, 51 FIRST STREET, NEW WESTMINSTER, BC
this is what it says on the PNW website
http://www.pnwisa.org/calendar.html