| The lateral shoots at the vegetative nodes of flax, Linum usitatissimum L., can be divided into three groups based on their degree of morphological development, type of vasculation and position. Shoots in group I, consisting of the cotyledonary nodes and nodes one though four (nodes labeled acropetally), are always found in the leaf axil and produce phloic and xylary connections with the main axis early in ontogeny. The cotyledonary shoots generally grow to a height approaching that of the terminal shoot. Nodes 5-19 (Group II) rarely produce lateral shoots and when present they lack any vascular connection with the main axis. Group III lateral shoots, on nodes 20 and higher, are found in the leaf axil or upon the leaf base. These shoots generally produce four prophylls and phloem but no xylem differentiates within their procambial traces. Group III shoots reach a height of approximately 80 m;Benzylaminopurine (BA) applied to the shoot tip stimulates the initiation of lateral shoots at group II nodes where shoot are normally absent. It also inhibits elongation of the main axis, but does not interfere with leaf initiation. Its effect on lateral shoots is different, and laterals are stimulated to elongate and produce more leaves. |
