A gene for tolerance to herbicide was assigned to chromosome 1 using a Texas marker stock having the morphological markers L ₁ ^L , lp1 and Lcx. This dominant marker was independent of the leaf shape marker on the short arm and 33.5 ± 9.2 cM from cotyledonary marker Lp ₁ that is on the long arm. The lc _x for white lint was associated with Lp1 of the tolerant parent such that lc _x lcx was common to plants unharmed by herbicide. The Lc _x for brown lint was independent of dominant leaf shape, but circa 30 ± 10 cM from the gene for tolerance. The undisturbed Lp ₁ - L1 ^L segregation for normal chromosome 1 reported in Endrizzi and Stein (1975) became a disturbed one in the present study. This disturbance could be attributed to foreign DNA. Since Lc _x has not been assigned in a formal manner to chromosome 1 and the three other brown linked markers have been placed on separate chromosomes, the Lc ₄ is deduced for presence on chromosome
1. The lp ₂ of chromosome 15 is part of a linkage group with multiple alleles for the green lint. The symbol for the dominant tolerance is pending instructions.