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The morphology and performance of near‐isogenic lines of soybeans with monogenically different pubescence types were investigated. Hairs of the normal, dense, and sparse types are similar, each consisting of a very long (1‐ to 3‐mm) cylindrical cell with one, two, or three basal cells. Hairs of curly pubescence are similar initially to normal hairs, but then become flat, curl, and tend to fall off. Glabrous plants have hair stubs made up of one to seven nearly isometric cells. Puberulent plant hairs consist of a single elongate (0.1 mm) apical cell with one, two, or three basal cells.Marked growth differences in the field were associated with differences in infestation by the potato leafhopper (Empoasca fabae (Harris)). Dense pubescent plants grew tallest followed in descending order by normal, sparse, curly, and glabrous types. Yields of lines with normal, dense, and sparse pubescence were similar, and superior to yields of the curly and glabrous lines.

F2 and F3 data from crosses of soybean strains with five aberrant pubescence types and strains with normal pubescence showed that each of the five differs from normal by a single gene pair and that the five loci segregate independently. Four of these genes occur in varieties from eastern Asia: P1 (glabrous), pc (curly pubescence), Pd (dense, three to four times the normal number of hairs), and Ps (sparse, a third to a fourth of the normal concentration of hairs); and the fifth originated as a mutant found in Iowa in 1924: P2 (puberulent). P1 (glabrous) appears to be epistatic to the other types, although Pd and Ps affect the density of the hair stubs visible on close inspection of glabrous plants. The genes pc and p2, affect the form of the hairs independently of the density effects of Pd and Ps. Pd and Ps interact with each other in an additive fashion in controlling hair density. The reported linkage between P1 p1 and R r (seed color) was confirmed.