Class 1: 0-0.15 m stem length; 1 stem per clump
Class 2: 0.15-0.3 m stem length; 1 stem per clump
Class 3: > 0.3 m stem length; 1 stem per clump
Class 4a: < 0.98 m stem length; 1-3 stems per clump
Class 4b: < 0.3 m stem length; 1-3 stem per clump
Class 4c:  0.3-1 m stem length; 1-3 stem per clump
Class 4d: 1-3 m stem length; 1-3 stem per clump
Class 4e: 3-6 m stem length; 1-3 stem per clump
Class 4f: 6-10 m stem length; 1-3 stem per clump
Class 5a: < 0.98 m stem length; 4-8 stems per clump
Class 5b: < 0.3 m stem length; 4-8 stems per clump
Class 5c: 0.3-1 m stem length; 4-8 stems per clump
Class 5d: 1-3 m stem length; 4-8 stems per clump
Class 5e: 3-6 m stem length; 4-8 stems per clump
Class 5f: 6-10 m stem length; 4-8 stems per clump
Class 5g: 10-15 m stem length; 4-8 stems per clump
Class 5h: 15-20 m stem length; 4-8 stems per clump
Class 5i: >20 m stem length; 4-8 stems per clump
Class 6a: < 0.98 m stem length; 9-15 stems per clump
Class 6b: < 0.3 m stem length; 9-15 stems per clump
Class 6c: 0.3-1 m stem length; 9-15 stems per clump
Class 6d: 1-3 m stem length; 9-15 stems per clump
Class 6e: 3-6 m stem length; 9-15 stems per clump
Class 6f: 6-10 m stem length; 9-15 stems per clump
Class 6g: 10-15 m stem length; 9-15 stems per clump
Class 6h: 15-20 m stem length; 9-15 stems per clump
Class 6i: >20 m stem length; 9-15 stems per clump
Class 7a: < 0.98 m stem length; >15 stems per clump
Class 7b: < 0.3 m stem length; >15 stems per clump
Class 7c: 0.3-1 m stem length; >15 stems per clump
Class 7d: 1-3 m stem length; >15 stems per clump
Class 7e: 3-6 m stem length; >15 stems per clump
Class 7f: 6-10 m stem length; >15 stems per clump
Class 7g: 10-15 m stem length; >15 stems per clump
Class 7h: 15-20 m stem length; >15 stems per clump
Class 7i: >20 m stem length; >15 stems per clump

Class 1: 0-0.15 m stem length; 1 stem per clump
Class 2: 0.15-0.3 m stem length; 1 stem per clump
Class 3: > 0.3 m stem length; 1 stem per clump
Class 4a: < 0.98 m stem length; 1-3 stems per clump
Class 4b: < 0.3 m stem length; 1-3 stem per clump
Class 4c:  0.3-1 m stem length; 1-3 stem per clump
Class 4d: 1-3 m stem length; 1-3 stem per clump
Class 4e: 3-6 m stem length; 1-3 stem per clump
Class 4f: 6-10 m stem length; 1-3 stem per clump
Class 5a: < 0.98 m stem length; 4-8 stems per clump
Class 5b: < 0.3 m stem length; 4-8 stems per clump
Class 5c: 0.3-1 m stem length; 4-8 stems per clump
Class 5d: 1-3 m stem length; 4-8 stems per clump
Class 5e: 3-6 m stem length; 4-8 stems per clump
Class 5f: 6-10 m stem length; 4-8 stems per clump
Class 5g: 10-15 m stem length; 4-8 stems per clump
Class 5h: 15-20 m stem length; 4-8 stems per clump
Class 5i: >20 m stem length; 4-8 stems per clump
Class 6a: < 0.98 m stem length; 9-15 stems per clump
Class 6b: < 0.3 m stem length; 9-15 stems per clump
Class 6c: 0.3-1 m stem length; 9-15 stems per clump
Class 6d: 1-3 m stem length; 9-15 stems per clump
Class 6e: 3-6 m stem length; 9-15 stems per clump
Class 6f: 6-10 m stem length; 9-15 stems per clump
Class 6g: 10-15 m stem length; 9-15 stems per clump
Class 6h: 15-20 m stem length; 9-15 stems per clump
Class 6i: >20 m stem length; 9-15 stems per clump
Class 7a: < 0.98 m stem length; >15 stems per clump
Class 7b: < 0.3 m stem length; >15 stems per clump
Class 7c: 0.3-1 m stem length; >15 stems per clump
Class 7d: 1-3 m stem length; >15 stems per clump
Class 7e: 3-6 m stem length; >15 stems per clump
Class 7f: 6-10 m stem length; >15 stems per clump
Class 7g: 10-15 m stem length; >15 stems per clump
Class 7h: 15-20 m stem length; >15 stems per clump
Class 7i: >20 m stem length; >15 stems per clump