xvi List of Illustrations 



FIG. PAGE 



81. Flowers of the Scotch pine (Pinus sylvestris). 288 



82. A large (" macro ") and two small (" micro") spores of 



Selaginella martensi (much magnified) 291 



83. Young carpel, mature carpel, and part of a mature cone 



of the silver fir (Abies pectinata} 297 



84. Spreading dogbane (Apocynum androscemi folium} 301 



85. Trap of the spreading dogbane (magnified) 305 



86. Common milk-weed (Asclepias cornuti} 307 



87. Trop of the milk-weed (magnified) 310 



88. A dogbane flower and its captive 315 



89. Nettle and Canada thistle (Urtica dioica and Cnicus 



arvensis} 318 



90. Burdock (Arctium Lappa} 321 



91. Common wild teasel (Dipsacus sylvestris) 324 



92. Irish gorse, furze or whin (Ulex Europceus} 327 



93. Single blossoms of the nettle 331 



94. Common thistle (Cnicus lanceolatus} 334 



95. White clover blossoms gathered in latter summer 340 



96. Pasture thistles ( Cnicus pumilis} 343 



97. Amaranth and sow-thistle {Amaranttis retroflexus and 



Sonchus asper} 348 



98. " Ribwort " (Plantago major} and " ripple grass " (Plan- 



tago lanceolata} 358 



; gga. Cork cells from the leaf scar of the horse-chestnut 



(much magnified) 365 



99^. Leaf scar of the horse-chestnut (magnified) 369 



100. Witch hazel (Hamamelis Virginica} 374 



101. Lengthwise section of a root-tip showing root hairs 



(much magnified) 391 



102. Branches of the alder and of the poplar-leaved birch 



showing numerous lenticels 393 



