52 PlNACEAE. 



1. Leaves very short and scale-like, alternately appressed 



on the stem. (Glyptostrobus). T. distichum imbricatum. 

 Leaves lanceolate, chiefly on flattened deciduous sprays. 2. 



2. Trees. 3. 



Dwarf. T. distichum nanum. 



3. Branches spreading. T. distichum. 

 Branches ascending. T. distichum pyramidatum. 

 Branches erect. T. distichum fastigiatum. 



THUJA. Arbor Vitae. 



Evergreen shrubs or trees with rather soft brownish ductless 

 wood without resin-passages ; rather slender twigs ; 4-ranked 

 minute scale-like leaves on finally deciduous fan-like foliar- 

 shoots ; no stipule-scars ; monoecious catkin- or cone-like naked 

 flowers ; and small cones with 2 winged seeds under each of the 

 rather thin scales. 



1. Leaves closely appressed. 2. 



Leaves spreading. (Retinospora forms). 13. 



2. Foliar-shoots mostly horizontal. 3. 

 Foliar-shoots vertical. 9. 



3. Oblong or conical. 4. 

 Round-topped. 8. 



4. Leaves green. 5. 



Leaves wholly or partly yellow. T. occidentalis lutea. 



Leaves tipped or variegated with white. 7. 



5. Tall. T. occidentalis. 

 Dwarf. 6. 



6. Irregular in shape. T. occidentalis cristata. 

 Compactly conical. T. occidentalis conica densa. 



7 .Leaves tipped with white. T. occidentalis alba. 



Leaves variegated with white. T. occidentalis argentea. 



8. Leaves green. T. occidentalis globosa. 

 Leaves entirely yellow when young. T. occidentalis aurea. 



9. Oblong or conical. 10. 

 Round-topped. 12. 



ir-. Leaves green, n. 



Leaves variegated with yellow. T. orientalis aureo-variegata. 



