1056 The Trees of Great Britain and Ireland 



PINUS MONOPHYLLA, One-leaf Nut Pine 



Pinus monophylla, Torrey, in Fremont, Report, 319, t. 4 (1844); Masters, in Gard. Chron. xx. 48, 

 f. 8 (1883), Ann. Bot. ii. 126 (1888), and Journ. Linn. Soc. {Boi.) xxvii. 269, f. 10 (1891), 

 XXXV. 584 (1904); J. D. Hooker, in Gard. Chron. xxvi. 136, f. 24 (1886); Sargent, Silva N. 

 Amer. xi. 51, t. 551 (1897), and Trees N. Amer. 12 (1905); Clinton-Baker, Illust. Conif. i. 33 

 (1909). 



Pinus Fremontiana, Endlicher, Syn. Conif. 183 (1847); Gordon, in Journ. Hort. Soc. iv. 293, 

 fig. (1849). 



Pinus cembroides, Zuccarini, var. monophylla, Voss, in Deut. Gartenrat, Beilage 123 (1904); Shaw, 

 Pines of Mexico, 5 (1909). 



A tree usually 25 to 30 ft., occasionally^ 40 to 50 ft. high, with a short trunk 

 rarely more than 5 ft. in girth. Bark reddish, divided by deep irregular fissures into 

 narrow connected scaly ridges. Young branchlets slender, grey, with scattered 

 minute pubescence. Buds cylindrical, obtuse, \ in. long ; scales few, closely imbri- 

 cated, greyish tinged with brown, ovate, apiculate, entire in margin. 



Leaves solitary, remotely placed on the branchlets, persistent for four or five 

 years or longer, incurved and directed forwards, rigid, terete, about \\ in. long, 

 ^ in. in diameter, marked with about twenty stomatic lines, and ending in a sharp 

 cartilaginous point; resin-canals, 3 to 14, marginal. Basal sheath \ in. long, its 

 upper part deciduous in the first year, while the lower part persists in the following 

 years as an irregular rosette of reflexed segments. According to Dr. Masters, the 

 solitary leaf is due to the arrested development in the bud of one leaf of a two- 

 leaved cluster. Occasionally the second leaf is fully developed, and two-leaved 

 clusters result. In cultivation adventitious shoots bearing flattish primordial leaves 

 are occasionally produced on the lower branches. 



Cones sub-terminal, short-stalked, \\ \.o 2 in. long ; scales few, with a thick 

 pyramidal non-prickly apophysis and a central umbo. Seed edible, about | in. 

 long and \ in. wide, brownish, oblong, full and rounded at the base, acute at the apex, 

 with a thin brittle shell, and a narrow wing, about \ in. wide, remaining attached 

 to the scale. Cotyledons 7 to 10. The primary flattened leaves, about an inch in 

 length, persist on the seedling till it is about five years old ; after which they become 

 shorter, buds forming in their axils and producing the adult leaves. 



This species is readily distinguished by its glaucous terete solitary ^ leaves, with 

 reflexed basal sheaths, and its peculiar buds. When two-leaved clusters appear the 

 leaves are semi-terete and entire in margin.' 



This pine is widely distributed, extending from the western base of the Wasatch 

 mountains in Utah, westward through the mountain ranges of Nevada, to the Sierra 

 Nevada in central California, and southwards to Arizona, and the coast ranges of 



1 According to Pinchot, U.S. Forest Service, Sylvical Leaflet 16 (1908), a few trees have been seen in the Tehachapi 

 mountains, 4 ft. in diameter and nearly 100 ft. in height. 



2 Solitary leaves occasionally occur as a sport in other pines, as in P. sylvestris, var. monophylla, but such cases 

 present no difficulty, as the buds, leaves, and basal sheaths are entirely different. 



' Cf. Engelmann, in Rothrock, Report Geol Surveys, vi. Botany, 259 (1878). 



