Proceedings of the Ohio State Academy of Science 103 



GENERAL KEY TO THE FAMILIES AND GENERA. 



Based on the flower and other characters. The number fol- 

 lowing the generic name refers to the list number. 



SPERMATOPHYTA. 



I. Ovules naked on an open carpel ; pollen falling directly on the 

 ovule ; trees or shrubs ; ours usually evergreen with nar- 

 row leaves, or with fan-shaped leaves and dichotomous 

 venation ; monoecious, rarely dioecious. 2. 



1. Ovules in a closed carpel or set of carpels; provided with a 



stigma for the reception of the pollen ; flowers more com- 

 monly showy. 4. 



2. GYMNOSPERMAE. 



2. Carpellate flowers developing as woody cones, the carpels ar- 

 ranged in spirals or opposite, each usually with 1-2 

 ovules ; or by coalescence forming a black or blue berry- 

 like fruit. 3. 



2. Carpellate flowers developing large plum-like fleshy seeds ; 



dioecious trees with fan-shaped leaves dichotomously 

 veined. Ginkgoaceae. 



a. Ginkgo, (i). 



3. Leaf-buds scaly ; carpels usually numerous ; leaves spirally 



arranged, the foliage leaves often situated on dwarf 

 branches. Pinaceae. 

 a. Ovuliferous scales woody; leaves needle-shaped, 

 2-5 on a dwarf branch. Pinus. (2). 



a. Ovuliferous scales thin; leaves linear or filiform, scat- 



tered or on thick wart-like dwarf branches, b. 



b. Leaves deciduous on wart-like dwarf branches, 



Larix. (3). 



b. Leaves scattered, persistent, c. 



c. Cones ]:)endulous. d. 



