There are three main subgenera of Pinus
, the subgenus Strobus
or soft pines), the subgenus Ducampopinus
and Lacebark pines), and the subgenus Pinus
, or yellow hard pines). This classification into the three subgenera is based on cone, seed and leaf characters:
- Subgenus Strobus Scale without a sealing band. Umbo terminal. Seedwings adnate. One fibrovascular bundle per leaf.
- Subgenus Ducampopinus Scale without a sealing band. Umbo dorsal. Seedwings articulate. One fibrovascular bundle per leaf.
- Subgenus Pinus Scale with a sealing band. Umbo dorsal. Seedwings articulate. Two fibrovascular bundles per leaf.
Notice that in many respects, subgenus Ducampopinus
is intermediate between (and possibly ancestral to) the other two subgenera. In many classifications, it is combined into subgenus Strobus
, but it could with equal justification have been included in subgenus Pinus
(as was done in an early classification by the Californian
botanist J G Lemmon in 1888), yet it does not sit comfortably in either so is best treated as a third subgenus in its own right. In general, cone and cone scale and seed morphology and leaf fascicle and sheath morphology are emphasized and this seems to result in a classification that has subsections of pines that are understandable and usually readily recognized by their general appearance.