Origin and Inheritance of Nectariless Cotton1

TLDR: Upland cotton, Gossypium hirsutum L., has leaf, extrafloral, and floral nectaries, and among the many interesting genetic markers which appeared in plants derived from hybrids of G. tomentosum, the absence of leaf and extrafloras was selected for transfer to Upland Cotton.

Abstract: CULTIVATED Upland cotton, Gossypium hirsutum L., has leaf, extrafloral, and floral nectaries. The nectar secreted attracts many insects and provides an important food for them. A nectary is usually found on the midrib on the lower side of each leaf. (Figure 1). Extrafloral nectaries are commonly found below the bracts (Figure 2) and also between and inside the bracts. Floral nectaries are located between the sepals and petals. (These have not been studied in the plant material reported in this paper.) G. tomentosum Nuttall is a wild cotton species, native to Hawaii, which has no leaf or extrafloral nectaries. G. hirsutum and G. tomentosum, tetraploid species with 2n = 52 chromosomes, produce a fertile Fj hybrid. Among the many interesting genetic markers which appeared in plants derived from hybrids of G. hirsutum X G. tomentosum, the absence of leaf and extrafloral nectaries was selected for transfer to Upland cotton. Rather early in the transfer program, C. E. Rhyne, Jr. suggested that