White spruce provenances from soils with limestone parent material, and non-limestone parent material were planted on calcareous and non-calcareous soils. The limestone provenances grew the most on calcareous soils: the non-limestone provenances grew the most on non-calcareous soils. Limestone ecotypes have evolved by natural selection.

A Scots pine clone bearing cone clusters transmitted precocity to a portion of its progeny resulting from crosses to clones having normal cone distribution. Inheritance appeared to be governed by a single major gene whose expression was dominant or recessive depending upon which clone it was mated to. Differences of reciprocal crosses indicated maternal or cytoplasmic influence. This genetic variation in precocity can be used to reduce the generation interval, thereby facilitating genetic studies and breeding programs. Seed yield per pollination bag was several times greater for cone clusters than for normally distributed cones although viable seed per cone was 20% less. This can reduce the cost of producing hybrid seed if artificial pollination is required.

The terpene composition of the leaf oils of the Rosendahl spruce, white spruce, and black spruce as isolated from provenances derived from Cromwell, Minnesota, was determined by gas–liquid chromatography. The chemical composition was found to reflect the hybrid origin of the Rosendahl spruce. This confirms that the leaf oil composition of Picea species may serve as a biochemical character in chemo systematic studies.

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Y'he s~lsceptibility of hard pines of the Lariciones groirp t o infestation by the E~rropecrrz pine shoot rnoth is postu!ated by