Crossability and Relationships of the California Big-Cone Pines

In the genus Pinus, much of the information about species crossability that has accumulated during the past three decades has reinforced ideas about the relationships of pines based on other kinds of evidence. There are some conspicuous exceptions to this generalization, however, and the most thoroughly investigated of these exceptions is Jeffrey pine (Pinus jeffreyi Grev. & Balf. ), an economically important forest tree of montane California and adjacent parts of Oregon, Nevada, and Baja California. Biochemically, this puzzling species is much like the Sabinianae Loud. (Macrocarpae Shaw), a group of big-cone pines endemic to California: Digger pine (P. sabiniana Dougl.), Coulter pine (P. coulteri D. Don), and Torrey pine (P. torreyana Parry). In its morphology, however, Jeffrey pine is very similar to ponderosa pine (P. ponderosa Laws.) and other members of the Ponderosae Loud., 2 a varied assemblage of yellow pines of western and southwestern North America. In its breeding behavior Jeffrey pine links these two well-defined groups through its ability to cross with members of both groups --- P. ponderosa and P. coulteri — in nature and under controlled conditions.

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Author(s): William B. Critchfield

Publication: Tree Improvement and Genetics - Lake States Forest Tree Improvement Conference - 1965