The Gladiolus 18: 93-94 (1943)
Colchicine Mutation of Gladiolus
Leo Matthers, Indianapolis

After four years of experimenting with colchicine gladiolus, I fully agree with the New York State Agricultural Station that it is much easier to cause mutation in dicotyledonous plants than it is in monocots.

In experimenting with gladiolus I have used over a dozen different lines of attack with as many as nine variations in the strength of solutions and the length of time for the treatment. In some cases I even combined the experiments with ethylene chlorhydrin. The colchicine used has always been an aqueous solution but the material treated included small bulbs, dormant bulblets, germinated bulblets, seeds, germinated and spikes which were given injections with a hypodermic needle.

For the present, at least, I have given up the treatment of small bulbs and bulblets because it is extremely difficult to reach the apical cells. A study of the Origin and Development of the Cormlet of Gladiolus by Sister Mary Joseph Therese Geiger, in the Gladiolus, 1942, shows the terminal growing point as quite deep and protected by several layers of cells Some of these cells might be removed so the apical cells could be treated but this would be an experiment for the laboratory and not for the outdoor gardener.

In a number of cases I have had the outer tissues of both small bulbs and bulblets effected but this was never permanent. Sometimes one or two pair of leaves would show evidence of mutation but succeeding leaves would grow normally . In other cases there would be extraneous root formations and of course these produced no reproductive material.

The most successful of all my experiments has been the placing of germinated seed in a 0.1% solution for a period of 2 hours. A large percentage of the seed will be killed with this treatment but from the ones which survived I have had three types of spikes:—

  1. A dwarfed condition in which the florets are very compactly placed around the stem.
  2. A double bud placement in which the florets are spaced rather symmetrically around the stem.
  3. Florets with a multiplicity of petals. In this last case the several spikes carried florets which ranged from the normal six petals to eleven petals. (See illustration opposite page 96.)

Of course, I realize that extra petals are not uncommon in gladiolus but I have never had them to the extent they appear in these treated glads . One disadvantage in working with gladiolus seed is the fact you do not have a trustworthy control with which to check your results. As yet no bloom from these colchicine treated glads has appeared to be of unusually large size.

Colchicine injection with a hypodermic needle seems to have possibilities. In fact one can see the greatly enlarged reproductive organs a few days after injection between the unopened buds. The writer has several dozen small bulbs grown from seed treated in this manner but what is within those bulbs must now remain a mystery until the growing season of 1943.