Leaf Abnormality: Flowers On The Petioles

Flowering on the petioles, also described as bud on leaf, is more of a growth abnormality than a mutation. Many strains will show this trait under certain conditions.

The occurence of flowers on the petioles was first published by John H. Schaffner in 1930 in The American Naturalist. This was one of several abnormalities noted in his paper about peculiar expressions in hemp.

"Hemp may be so developed in a given short-light-temperature complex that some of the petioles at the base of the inflorescence will bear one or more flowers on the upper side. Sometimes there is a regular row of flowers on the petiole. Now is it the hereditary nature of the hemp to produce flowers on the leaf petiole? I would say that it most certainly is. But again this reaction is determined by a certain specific aggregate of ecological conditions. Under one set of ecological factors the hemp has such a reaction; under another set of ecological factors no such reaction takes place."

As Schaffner explains, this developmental phenomena usually occurs with a certain combination of short days and certain temperatures, but it is different between strains and very unpredictible in general. Several variations may occur, depending on the stage of flowering or rejuvination. There may be a single flower, or a whole string of them. Sometimes additional leaves or even an entire branch emerging from the petiole. Usually these stem from the junction of the leaflets, but they may also grow from anywhere along the petiole.