175] ENGELMANN—REVISION OF THE GENUS PINUS, ETC. 15 
I now propose an arrangement of the species of Pinus based 
upon the more essential characters above analyzed, and, though 
I by no means claim it to be a faultless one, I expect that it will 
deserve the character of a natural one as much as any that can 
be devised. I find with Endlicher the most valuable character in 
the fruit scale, or rather, to speak more correctly, I find that the 
form of the fruit scale in this genus corresponds with a series of 
other characters which constitute two very natural sections of tlge 
genus. My section S¢rodus in a wider sense includes his Strobus 
and Cembra, and my Pinaster, also enlarged, comprises all his 
other sections, viz. Pseudo-strobus, Teda, Pinaster,and Pinea. 
The subsections are distinguished by the position of the ducts 
within the leaf, whether peripheral, parenchymatous, or internal. 
Subordinate to this character is the subterminal or lateral position 
of the female ament and the cone. Only after this may the num- 
ber of leaves ina sheath be taken into consideration, and perhaps 
the presence or absence of strengthening cells around the ducts. 
It will be found that thus not only natural but to some extent 
even geographical alliances are best preserved. I enumerate only 
such species or subspecies (these in brackets) which I have been 
able to examine myself; the list, however, will be found nearly 
complete. The nomenclature of Parlatore in DC. Prod. xvi.2 
is adopted unless otherwise stated. , 
Sect. I. STROBUS. Apophysis with a marginal unarmed umbo, — 
ge 
nerally thinner; cones subterminal ; leaves in fives, their 
sheaths loose and deciduous; anthers terminating in a knob, or 
a few teeth, or ina short incomplete crest; wood softer, lighter, 
less resinous. 
§ 1. Eustrosr. Ducts peripheral.--Northern or mountain species of 
the Old and New World. 
* Wings longer than the seeds; leaves sharply serrulate, denticu- 
late at tip. 
+ Strengthening cells few, none around ducts. 
P. Strobus, monticola, excelsa, Peuce, parvifiora,? Bonapartea,® Ayaca- 
utte. 
++ Strengthening cells abundant under the epidermis and 
surrounding ducts. 
P. Lambertiana. : 
** Wings much shorter than seeds; leaves mostly entire, not 
denticulate at tip. 
‘ » 
. 
P. flexilis, (albicaulis,) pygmea. 
* 
