Nov., 1904.] Leaf Expansion of Trees and Shrubs. 211 



the 14th of May. A period of fifteen days, therefore, intervened 

 between the leafing of the first individuals and the last. In such 

 cases the period marked was the time when the leaves were 

 appearing rather commonly rather than the first individuals. 

 The willows showed interesting peculiarities. Some species 

 appear very early, others quite late. If this is the usual course, 

 the time of leafing might be of some value in determining species 

 in early spring. Some of the maples and buckeyes are the most 

 sudden in the unfolding of their leaves. The catalpas, coffee- 

 bean, fringe-tree, and hop-tree develop the foliage very slowly. 

 It was also observed that many trees begin to leaf at the top. 



April 1. 

 Syringa vulgaris L. 



April 2. 



Larix laricina (Du R.) Koch., L. decidua Mill., Salix babylonica L. 



April 5. 

 Salix fragilis L., Lonicera tartarica L., L. korolkowi Stapf. 



April 7. 

 Salix alba L. 



April 8. 

 Prunus serotina Ehrh. 



April 11. 



Euonymus atropurpureus Jacq., E. europseus L., Ribes aureum 

 Pursh., Cydonia japonica Pers., Sambucus canadensis L. 



April 14. 

 Euonymus obovatus Nutt., Spiraea hypericifolia DC. 



April 16. 

 Rubus occidentalis L., Prunus virginiana L. 



April 18. 

 Aesculus glabra Willd. 



April 21. 

 Philadelphus coronarius L. 



April 23. 



Betula alba L., Sorbus aucuparia L., Symphoricarpos racemosus Mx.,. 

 S. symphoricarpos (L.) MacM. 



April 25. 

 Staphylea trifoliata L., Acer negundo L., Comus baileyi Coult. and 

 Ev., Ligustrum vulgare L., Viburnum opulus L. 



April 26. 



Berberis vulgaris L., Rosa rubiginosa L., Malus malus (L.) Britt., 

 Prunus japonica Thunb., Comus alba L. 



