The Geography of Phytochemical Races

3.2 North American Conifers 157
Table 3.3 Additional studies of Pinus terpenes
Species Common name Reference
P. cembroides Zucc. Mexican piñon pine Zavarin and Snajberk (1985)
P. fl exilis James Limber pine Zavarin et al. (1993)
P. monophylla Torr. Single-leaf piñon Snajberk et al. (1982)
Zavarin et al. (1990)
P. nigra Arn. European black pine Rafi and Dodd (1996)
P. quadrifolia Parl. Parry piñon Snajberk et al. (1982)
P. radiata (Little) D. Don Monterey pine Cool and Zavarin (1992)
P. remota (Little) Bailey & Snajberk and Zavarin (1986)
Hawksworth
3.2.5 Pseudotsuga
Pseudotsuga is represented in North America by two species, P. menziesii (Mirb.)
Franco, the Douglas fi r, and P. macrocarpa (Vasey) Mayr, commonly known as big
cone Douglas fi r. True Douglas fi r is widespread, ranging form British Columbia
south through the Coast Ranges, along the Cascade Range, in the Rocky Mountains,
in the Sierra Nevada, with a small population near Lompoc, California (Santa
Barbara County). Big cone Douglas fi r occupies a much smaller range in southern
coastal California. Both species have been subjected to detailed analysis of their
monoterpenes.
A study of terpene composition of Douglas fi r by von Rudloff (1973) established
existence of geographic pattern in the volatile components. Zavarin and Snajberk
(1973b) examined P. menziesii using specimens collected from its entire range.
Four distinct chemical races were found to exist: (1) the coastal race (Oregon,
Washington, and British Columbia) characterized by high levels of sabinene
and terpinolene; (2) the northern inland race (Rocky Mountains of Canada and
the United States north of the Snake River Basin) characterized by high levels of
α-pinene with only traces of sabinene; (3) the southern inland race, characterized
by high levels of α-pinene and limonene with only traces of sabinene; and (4) the
Sierra Nevada race (central Sierra Nevada Mountains) characterized by high levels
of α-pinene and β-pinene and traces of sabinene. Other compounds identifi ed,
but not fi guring in the defi nition of chemical races, were tricyclene, α-thujene,
camphene, 3-carene, myrcene, β-phellandrene, γ-terpinene, and trans-ocimene.
The coastal race conforms to P. menziesii var. menziesii, whereas the inland races
accord well with P. menziesii var. glauca (Beissn.) Franco, the form known from the
Rocky Mountains. There is no established morphological equivalent to the Sierra
Nevada race; trees from that area are usually referred to var. menziesii. Zavarin
and Snajberk (1975), however, summarized differences between trees harvested in
the Sierra Nevada Mountains and those harvested in northwestern California with
regard to commercial applications, particularly in the manufacture of plywood or
the production of composite materials (particle board). Differences in such factors