Cellulose synthesis and other fiber characteristics during secondary cell wall development have been studied on several species, i.e.,G. barbadense (Pima S-7),G. hirsutum (Maxxa, Texas Marker 1),G. arboreum (A2-Asian 163),G. herbaceum (A1-Africa 51). Fiber length and cellulose deposition during the transitional period shows significant differences among varieties. The relationships between fiber characteristics and development are being further studied.