308 PINUS. 



five-leaved, thus leaving the position of the subsequently discovered 

 species P. monopliylla (one-leaved), P. Parry ana (four-leaved), P. cem'broides > 

 P. Elliottii and others (two three leaved) ambiguous. Cognisance has. 

 since been taken of other characters in connection with those of the 

 leaves, and among the most iiseful of these for classificatory purposes 

 are the form of the cone scales, the seeds and the anatomical structure 

 of the leaves, especially the position and number of the resin canals. 

 Combining these and some subordinate characters, the late 

 Dr. Engelmann of St. Louis, U.S.A., elaborated the most scientific 

 sectional arrangement of the Pines that has yet been published,* and 

 which in a more or less modified form is adopted by recent authors. 

 In a* practical sense Dr. Engelmann's sections have the disadvantage of 

 occasionally grouping together trees of very different habit and aspect 

 on account of the greater value set upon the anatomical characters of 

 the leaves, and which can be ascertained only with the aid of the 

 microscope. 



The following sectional arrangement of species cultivated in Great 

 Britain is framed in respect of the leaves and cones only which are 

 for the most part easily accessible, and it may thence serve for 

 practical use.f 



STROBI. Leaves in bundles of five. Cones pendulous, much longer 

 than broad ; scales relatively thin and terminating in a blunt point. 

 Seeds prominently winged : 



Ayacahuite, excelsa, Lambert iana, monticola, pentapliylla, Peuke, Strobus- 

 CEMBR.E. Leaves in bundles of five. Cones erect or horizontal, not 

 much longer than broad ; scales with or without a thickened apophysis. 

 Seeds large and obscurely winged : 



Albicaulis, JBalfouriana, Cembra, flexilis, koraiensis, parviflora. 

 EDULES. Leaves in bundles of one five. Cones sub-terminal, 

 globose, the central scales only fertile, thickened, with a prominent 

 and armed apophysis. Seeds large with" rudimentary wings : 

 Cembroides, edulis, monopliylla, Parryana. 



T^ED^:. Leaves in bundles of three. Cones sub-terminal or lateral, 

 ovoid, occasionally elongated; scales much thickened, the apophysis 

 often with a stout armed umbo. Seeds prominently winged : 



Bungeana, Coulteri, Gerardiana, palustris, patula, ponderosa, radiata y 

 rigida, Sabiniana, Tceda, tuberculata. 



PINASTER. Leaves in bundles of two. Cones lateral and mostly 

 persistent, often large and clustered ; scales much thickened, the 

 apophysis blunt or armed with a sharp spine. Seed wings variable : 

 Contorta, mitis, muricata, Pinaster, pungens, pinea, pyrenaica. 

 SYLVESTRES. Leaves in bundles of two. Cones sub-terminal and 

 mostly falling off, ovoid-conic and relatively small; scales slightly 



* Revision of the Genus Finns in the Transactions of the Academy of Science of 

 St. Louis, Vol. IV. (1880). 



t Several of the Mexican Pines with leaves in bundles of five, of which the best known 

 in this country is Pinus Montezumce, cannot be included in either of the sections STROBI 

 or CEMBRA in consequence of the scales of their cones having a distinct apophysis with a, 

 central umbo ; they thence come under the section Paeudo-Sjtrobus of Endiicher. 



