20 THE FINES OK MEXICO. 



Pi XL'S PSEUDOSTROBUS VAR. TEXUIFOLIA, M VAR. 



Pinus tenuifolia Bentham, PL Hartw. 92 (1842). Endlicher, Syn. Conif. 155 (1847). 



Parlatore, DC. Prodr. xvi, pt. 2, 400 (1868). Hemsley, Bot. Biol. Cent. Am. iii, 189 



(1883). 



Cones ovate or long-ovate, their peduncles persistent on the cones ; hypoderm of the leaves 

 remarkably developed, extending from the epiderm to the endoderm and forming partitions 

 across the green tissue. 



Abundant in the western and south western states at subtropical altitudes, and extending 

 into Central America as far as north western Nicaragua (Seemann in Pirn & Seemann Dottings 

 on the Roadside, 55). 



Hartweg, 620, (type) Guatemala. Nelson, 2536 (398579) Miahuatlan, Oaxaca ; 3128 (39S5S9) San 

 Cristobal, Chiapas ; 41 18 (39S61 1) La Laguna, Jalisco. Goldman, 997 (39S800) Ixtapa, Chiapas. Rose, 1671 

 (300527) Colomas, Sinaloa; 2263 (301 176-7) State of Durango ; 3025 (3019S2) Boloftas to Guadalajara, 

 Jalisco. Shaw, Com and Uruapan, Michoacan ; San Felipe, Oaxaca. 



The peculiar hypoderm of the variety tenuifolia is least conspicuous in Hartweg, No. 620, and in Rose, No. 

 167 1. The character may be followed through various stages until it reaches its greatest development in Rose, 

 3025. At Uruapan, where this form is abundant, trees at the base of the mountains, in all other respects like 

 those higher up the slope, bear leaves without the peculiar hypoderm. Nelson, No. 6888, with a tenuifolia 

 cone has leaves with the normal section of the species. These exceptions, together with the unreliability of 

 the persistent cone-peduncle, make it impossible to find specific characters for Bentham's P. tenuifolia. Its 

 habit and bark are identical with those of P. pseudostrobus . 



In all the forms the striking character is the habit of the young tree, with its straight, slender, tapering 

 stem of long internodes, its smooth bark, slender branches and drooping leaves. The persistent smooth bark 

 of the branches separates this species from those forms of P. Montezumae which bear cones and leaves similar 

 to those ot P. pseudostrobus. 



PLATE XIII. 



Fig. 1. Cone of Nelson 312S. Fig. 6. Cone and leaves of Rose 3025. 



" 2. Leaf-section, magn. 30 diam. " 7. Leaf-section, magn. 30 diam. 



" 3. Cone of Nelson 2535. " 8. Leaf-section of Hartweg 620, magn. 30 diam. 



" 4. Leaf-section, magn. 30 diam. " 9. Tree at Uruapan. 



" 5, Leaf-section of Rose 1671, magn. 30 diam. 



