Pseudotsuga Carrière 1867

Introduction

Pseudotsuga is a small genus of approximately five species distributed in eastern Asia and western North America. Pseudotsuga menziesii, with a distribution from western Canada to central Mexico, is one of the most economically important timber species in the world.

Characteristics

Medium to tall trees with straight stems and upright to spreading branches. Spirally arranged leaves (needles), reddish brown ovoid-conical vegetative buds. Reddish brown ovulate cones are pendulous with exserted bracts (Farjon 1990).

Discussion of Phylogenetic Relationships

Farjon (1990) recognized only four species of Pseudotsuga: Pseudotsuga macrocarpa from southern California, Pseudotsuga menziesii ranging from Canada to south-central Mexico, Pseudotsuga japonica from southern Japan, and Pseudotsuga sinensis from China. Included in the ToL phylogeny is also P. wilsoniana from Taiwan. In addition to P. wilsoniana, several other species have been segregated from Pseudotsuga sinensis (P. forrestii, P. salvadorii, P. gaussenii, P. brevifolia, P. xichangensis), but these have not been widely accepted. Mexican botanists tend to recognize four segregate species of Pseudotsuga menziesii var. glauca in Mexico: P. macrolepis, P. rehderi, P. guinieri, and P. flahaultii (Martínez 1963).

Relationships among the widely-accepted species were studied by Strauss et al. 1990 using DNA restriction fragments and by Gernandt and Liston (1999) using nuclear ribosomal DNA.

Other Names for Pseudotsuga Carrière 1867

• Douglas-fir

References

Farjon, A. 1990. Pinaceae: drawings and descriptions of the genera Abies, Cedrus, Pseudolarix, Keteleeria, Nothotsuga, Tsuga, Cathaya, Pseudotsuga, Larix and Picea. Koeltz Scientific Books, Königstein.

Gernandt, D. S. and A. Liston. 1999. Internal transcribed spacer region evolution in Larix and Pseudotsgua (Pinaceae). Amer. J. Bot. 86:711-723.

Martínez, M. 1963. Las Pináceas Mexicanas. 3rd edition. Universidad Nacional Autónoma de México, Mexico City.

Strauss, S. H., A. H. Doerksen, and J. R. Byrne. 1990. Evolutionary relationships of Douglas-fir and its relatives (genus Pseudotsuga) from DNA restriction fragment analysis. Canad. J. Bot. 68:1502-1510.