EXPLANATION OF THE PLATES. 397 



2, Saururus cernuus; part of the flowering stem, a small 

 specimen, natural size ; 2^, a flower magnified. 



3, Euphorbia corollata, an involucre with the fertile 

 flower stalked and protruded, natural size ; Za, the invo- 

 lucre laid open, to show the solitary fertile and the 12 ste- 

 rile flowers ; 3Z>, a sterile flower with its bract ; 3c, cross- 

 section of the 3-carpelled fruit ; all magnified. 



4, Acalypha Yirginica, part of the plant, natural size ; 

 4:«, a sterile flower, highly magnified ; 4^, a fertile flower, 

 natural size ; 4(?, pistil, magnified. 



5, Ulmus racemosa, fiowers ; 5«, a receme in fruit ; both 

 the natural size ; 55, a flower detached ; 5<?, the pistil 

 with the ovary vertically cut open ; both magnified. 



6, Celtis Americana, a small branch with a flower pre- 

 served, natural size. 



7, Carpinus Americana, a fertile ca4:kin in fruit (involu- 

 cral scales large and 3-lobed), natural size. 



8, Pilea pumila, summit of a fertile plant, natural size ; 

 8«, a sterile flower ; 8J, a fertile flower ; 8c, a sepal with 

 a rudimentary stamen ; all magnified. 



9, Betula, an anient of staminate flowers ; 9<35, an anient 

 of pistillate flowers ; both figures of natural size ; %, a 

 pistil with the ovary vertically dissected ; 9c, vertical sec- 

 tion of a ripe fruit, showing the developed cell with its 

 single seed, and a mere trace of the obliterated second one ; 

 96?, the pistils with their subtending bract ; all magnified. 



10, Fagus sylvatica, the soft-prickly coriaceous involucre 

 of the nut, of natural size. 



11, Salix Candida, anient of a sterile plant, the natural 

 size; 11«, one of its fiowers slightly magnified; 115, 

 ament of a fertile plant, of natural size; lie, a pistillate 

 flower, magnified. 



12, Populus grandidentata, a scale taken from an ament. 



