=Abies balsamea=, =290= =Aceracea=, =239= =Acer=, =239= Negundo, =240=, 241, 298, 300 =Negundo= variety =violaceum=, =242= =nigrum=, =246=, 247, 299 =pennsylvanicum=, =295= =rubrum=, =244=, 245, 298, 300 =rubrum= variety =Drummondii=, =244= =rubrum= variety =tridens=, =246= =saccharinum=, 242, 243, 300 =saccharum=, 248, 249, 298, 299 =saccharum= variety =glaucum=, =248= =saccharum= variety =Schneckii=, =250= =saccharum= variety =Rugelii=, =250= Acknowledgments, 16 =Adelia=, =282= =acuminata=, =282=, 283, 300 =Æsculaceæ=, =251= =Æsculus=, =251= _flava_ variety _purpurascens_, _253_ =glabra=, =251=, 252, 300 =octandra=, =253=, 254, 300 =Ailanthus altissima=, =237=, 238 _glandulosa_, _237_ Alder, 90, 300 smooth, 92, 93 speckled, 90, 91 =Alnus=, =90=, 297 =incana=, 13, =90=, 91, 297, 300 =rugosa=, 13, 90, =92=, 93, 300 =Altingiaceæ=, =166= =Amelanchier canadensis=, =177=, 178 =lævis=, =177=, 179, 298, 299 =Amygdalaceæ=, =216= =Anonaceæ=, =161= Apple, American crab, 172, 173, 299 Iowa crab, 174 narrow-leaved crab, 174, 175 western crab, 174, 176 thorn, 180 Arbor-Vitæ 32, 33, 300