ANALYTICAL KEY 



TO THE GENERA OF PLANTS INCLUDED IN THIS BOOK, 

 BASED CHIEFLY ON THE CHARACTER OF THE LEAVES 



I. Leaves parallel-veined, alternate, persistent, clustered at the end of the stem or 

 branches. Monocotyledons. 



Stem simple; leaves stalked. 

 Leaves fan-shaped. 

 Leaf stalks unarmed. 



Rachis short; leaves usually silvery white below. 



Leaves 2-4'in diameter (green below in No. 2), their segments undivided at 

 apex. Thrinax (p. 96). 



Leaves 18'-24' in diameter, their segments divided at apex. 



Coccothrinax (p. 100). 

 Rachis elongated ; leaves green below, their segments divided at apex. 



Sabal (p. 101). 

 Leaf stalks armed with marginal teeth or spines. 



Leaf stalks furnished irregularly with broad thin large and small, straight or hooked 

 spines confluent into a thin bright orange-colored cartilaginous margin; leaves 

 longer than wide, divided nearly to the middle into segments parted at apex and 

 separating on the margins into thin fibres. Washingtonia (p. 104). 



Leaf stalks furnished with stout or slender flattened teeth; leaves suborbicular, 

 divided to the middle or nearly to the base into segments parted at apex; seg- 

 ments of the blade not separating on the margin into thin fibres. 



Acoelorraphe (p. 105). 

 Leaves pinnate. 



Leaves 10-12 in length, their pinnae 2|-3 long and often 1| wide, deep green. 



Roystonea (p. 107). 



Leaves 5-6 long, their pinnse 18' long and 1' wide, dark yellow-green above, pale and 



glaucous below. Pseudophoenix (p. 109). 



Stem simple or branched; leaves sessile, lanceolate, long- and usually sharp-pointed at 



apex. Yucca (p. 110). 



H. Leaves i-nerved, needle-shaped, linear or scale-like, persistent (deciduous in 

 Larix and Taxodium). Gymnospermae. 



1. LEAVES PERSISTENT. 



a Leaves fascicled, needle-shaped, in 1-5-leafed clusters enclosed at base in a membrana- 

 ceous sheath. Pinus (p. 2) . 



aa Leaves scattered, usually linear. 



6 Leaves linear, often obtuse or emarginate. 



Base of the leaves persistent on the branches. 



Leaves sessile, 4-sided, or flattened and stomatiferous above. Picea (p. 34). 

 Leaves stalked, flattened and stomatiferous below, or angular, often appear- 

 ing 2-ranked. Tsuga (p. 42) . 

 Base of the leaves not persistent on the branches; leaves often appearing 

 2-ranked. 



Leaves stalked, flattened, stomatiferous below; winter-buds pointed, not 



resinous. Pseudotsuga (p. 47). 



Leaves sessile, flattened and often grooved on the upper side, or quadrangular, 



rarely stomatiferous above, on upper fertile branches often crowded; 



winter-buds obtuse, resinous (except in No. 9). Abies (p. 50). 



bb Leaves linear-lanceolate, rigid, 'acuminate, spirally disposed, appearing 2-ranked 



by a twist in the petiole. 



