146 
VINNIE A. PEASE 
Gymnosperms 
1. Abies grandis 6. Pseudotsuga taxifolia 
2. Juniperus scopulorum 7. Taxus hrevifolia 
3. Picea sitchensis 8. Thuja plicata 
4. Pinus contorta 9. Tsuga heterophylla 
5. Pinus monticola 
Angiosperms 
(a) Transitional Forms. — Those species which are deciduous under 
certain conditions and under others partly evergreen. 
10. Rhamnus purshiana it. Vaccinium parvifolium 
(b) Sub-evergreens. — Those holding the leaves of one season only 
until the leaves of the next season are able to carry on the photosyn- 
thetic work of the plant. These species are not noticeably affected by 
external conditions. 
12. Arbutus menziesii * 16. Rubus laciniatus 
13. Ceanothus velutinus 17. Rubus pedatus 
14. Linnaea americana 18. Rubus ur sinus 
15. Micromeria douglasii 
(c) True Evergreens. — Species which usually hold their leaves 
longer than the second season. These are noticeably affected by 
external conditions. 
19. Arctostaphylos tomentosa 26. Kalmia polifolia 
20. Arctostaphylos uva-ursa 27. Ledum groendlandicum 
21. Berberis aquifolia 28. Oxy coccus oxy coccus inter- 
22. Berberis nervosa medius 
23. Chimaphila menziesii 29. Pachistima myrsinites 
24. Chimaphila umbellata 30. Rhododendron californicum 
25. Gaultheria shallon 31. Vaccinium ovatum 
Stark (16), in 1876, spoke of leaf duration as "not a new subject," 
yet at the same time declared his inability to find anything bearing on 
the subject in botanical literature. He made extensive observations 
on the native and introduced conifers in his large private grounds in 
the British Isles, and distinguished between true leaf fall, as shown in 
Taxus and Abies, and the shedding bodily of twigs (cladoptosis) as 
shown in Thuja, Pinus, and Sequoia sempervirens. He also remarked 
that old trees of Picea and Abies held their leaves for a shorter time 
than saplings. 
Legget (10), in 1876, recognized the influence of climate on leaf 
duration especially in transitional forms. 
