THE PINES OF MEXICO. 



4. PINUS AYACAHUITE EHRENB. 



Pinus ayacahuite Ehrenberg, Linnaea, xii, 492 (1838). Loudon, Encycl. Trees & 

 Shrubs, 1023, figs. 1920-1 (1842). Endlicher, Syn. Conif. 149 (1847). Parlatore, DC. 

 Prodr. xvi, pt. 2, 406 (1868). Masters, Gard. Chron. ser. 2, xviii, 492, fig. 83 (1882). 

 Hemsiey, Bot. Biol. Cent. Am. iii, 186 (1883). Lawson, Pinet. Brit, i, 9, fig. (1884). 

 Nicholson, The Garden, xxv, 193, fig. (1884). Veitch, Man. Conif. ed. 2,311, fig. (1900). 



Leaves with deciduous sheaths, in fascicles of 5, 10-20 cm. long, serrate ; stomata ventral; 

 resin ducts external and varying in number from 2 to 8. Conelets in clusters of 2 or 3, on 

 long stout peduncles, cylindrical, their scales thin and closely imbricated. Cones on long 

 peduncles, pendent, 20-45 cm. long, straight or curved; apophyses dull, occasionally sublustrous, 

 pale yellowish or reddish brown, often conspicuously corrugated, their apices reflexed, recurved 

 or revolute in various degrees. Seeds variable in the size of both wing and nut. Branchlets 

 pale brown, at first pubescent, becoming ashen -gray and glabrous ; the cortex persistently 

 smooth for many years. 



A large tree growing at cool temperate altitudes from Central America to the borders of the 

 United States. 



Nelson, 982 (398556) west of Yalalag, O.ixaca ; 2188 (398572) Chilpancingo, Guerrero; 2520 (398575) 

 Miahuatlan, Oaxaca; 3186 (398592) San Cristobal, Chiapas; 3650 (398596) Chaucol, Guatemala; 7060 (399401) 

 Omilteme, Guerrero Goldman 988 (398797) San Cristobal, Chiapas. 



The leaf-section of P. ayacahuite is variable. The weak hypoderm and few resin ducts of some leaves resemble 

 those of P. Strobus L., others with conspicuous thick-walled hypoderm resemble the leaf-sections of P. Lamber- 

 tiana Dougl. or of P.flexilis James. According to Engelmann some leaves bear dorsal stomata, but this is probably 

 sporadic and unusual. 



Plate IV represents the typical form of the species bearing seeds with long wings. They are all from Guate- 

 mala or from the southern Mexican States. The wing-imprint on the different cone-scales indicates considerable 

 variation in length even among the southern forms. 



PLATE IV. 



Fig. 1 



Leaves of Nelson 7060. 



" " " 2520. 

 " " 3186. 



" " " 2188. 

 Leaf-section of Nelson 2520 magn. 30 diam. 



u a u n y g u u u 



" " " " 2188 " " " 



u tt it u 082 " " " 



c i< 1' ?i86 " " " 



Fig. 10. Cone scale of Nelson 982. 



" n. " " " " 7060. 



" 12. " " " " 3186. 



" 13. " " " " 2188. 



" 14. " " " " 2520. 



" 15. " " " " 3650. 



" 16. Seed of Nelson 3650. 



" 17. Cone of Nelson 3650. 



