Abstract
Among conifer species, the resolution of malate dehydrogenase (MDH) band patterns was greatest in Douglas-fir in which there was evidence of four loci, two of which regularly form a heterodimeric product. MDH in lodgepole pine, white spruce, and Sitka spruce also appear to be under control of four loci, while MDH in the true firs, white and grand fir, and western red-cedar appear to be controlled by only three loci.