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1 8. Ruhus pedatus J. E. Smith. The writer found a single speci- 
men, and that bore leaves of two seasons' growth. 
19. Arctostaphylos tomentosa Dougl. The writer had access to only 
one specimen, a shrub which has stood for several years in the north- 
west angle of a 3-story building on the University campus. This 
showed a leaf duration of 4, 5 and 6 years on various branches. 
20. Arctostaphylos uva-ursa Spreng. Shortest leaf duration ob- 
served, 2 years; average, 3 years; extreme, 5 years. 
21. Berberis aquifolium Pursh. Shortest leaf duration observed, 
1 year; average, 2-4 years; extreme, 6 years. Not found usually in 
shaded situations. A dry climate shortens its leaf duration. 
22. Berberis nervosa Pursh. Shortest leaf duration observed, 2 
years; average, 3-4 years; extreme, 8 years. Plants growing in the 
shade show a- longer leaf duration than those growing in the open. A 
dry climate accents the difference in duration between leaves in the 
open and those in the shade. 
23. Chimaphila menziesii Spreng. Shortest leaf duration observed, 
2 years; average, 4-5 years; extreme, 8 years. This species was found 
only in a limited area on San Juan Island. 
24. Chimaphila umbellata Nutt. Shortest leaf duration observed, 
I year; average, 2-4 years; extreme, 7 years. A dry climate tends to 
increase its leaf duration. 
25. Gaidtheria shallon Pursh. Shortest leaf duration observed,. 
I year; average, 2-4 years; extreme, 6 years. Shade plants under 
typical moisture conditions have a shorter leaf duration than plants 
in the open, while under dry conditions plants in the open have the 
shorter leaf duration. Plants growing in sphagnum about the margins 
of peat bogs resemble in growth-habit plants growing in the open in 
ordinary soil, but have a decided tendency toward shorter leaf duration. 
26. Kalmia polifolia Wang. Shortest leaf duration observed, i 
year; average, 2 years; extreme, 3 years. In contrast to Ledum, 
shaded plants showed a tendency to shorter leaf duration, and plants 
which had been growing for several years in the experimental gardens 
were entirely bare of leaves when observed in December. 
27. Ledum groenlandicum Oeder. Shortest leaf duration observed, 
I year; average, 2-4 years; extreme, 5 years. Plants in an open peat 
bog showed the shortest leaf duration. Plants which had been trans- 
ferred to the experimental gardens of the university campus several 
years ago showed a marked tendency to increased leaf duration. 
