The transition from root to stem in G. hirsutum is completed in the upper portion of the hypocotyl. The primary root is generally a tetrarch, exarch proto-stele. 4 transition bundles are formed, each consisting of 2 units. In alternate bundles these units are separated by wide rays. At the level of the cotyledonary plate, 1/2 unit of each original transition bundle that matured first, and the 2 units of the 1 bundle, in which the rays are narrow, diverge into one cotyledon. The other bundles become the vascular traces of the 2nd cotyledon.