Leaf Mutation: Simple Leaves

The simple leaf mutation, also described as palmately lobed, webbed leaf, duckfoot, or pinnatifidofilla has a long history. Although it is possible that the mutation originated only once, it is likely that it has arisen several times and has been selected and maintained because of the conspicuous phenotype. There are several strains which have similar leaf morphology, including the Ducksfoot, Hawaiian Webbed Indica, Strawberry Web, Patte Canard, and some individuals of the landrace hemp from the Ferrara region of Italy.

Photographs of the webbed leaf mutation were first published by Walter Scott Malloch in 1922 in The Journal of Heredity. The mutation was presented as an interesting phenotype that was uncovered during an investigation of sex inheritance in the species. This mutation and a sectoral chlorophyll mutation were shown as evidence that Cannabis could be a useful model to study general inheritance.

“In an obligatory cross-fertilized genus like Cannabis we would naturally expect new forms to appear as a result of inbreeding. A mutant form was sent to the writer by Mr. L. H. Dewey of the United States Department of Agriculture and Professor A. H. Wright of the University of Wisconsin. This mutant is a simple leafed form which appeared in a strain of Ferramington. Instead of having the normal digitate leaf usually found in hemp, the mutant is characterized by a palmately cleft leaf as shown in Figure 20. The leaflets of the normal digitate leaf appear to have grown together as the normal number of midribs is present with an equal number of lobes. There is usually an unequal growth of tissue between the midribs which results in excess leaf surface thus causing a folded and wavy appearance of the leaf.”

The Ferramington strain of hemp, which contained the recessive mutation, was bred by Lyster Dewey, starting in 1916. The parent lines were Kymington (a selection of ‘Minnesota No. 8’ bred by Mr. Dewey beginning in 1914) and the landrace from Ferrara, Italy.

“The Ferramington variety has been developed by successive selection from the progeny of a cross made in 1916. In that year a row of Ferrara, the best hemp of northern Italy, was grown in the plot of Kymington, and all of the Ferrara staminate plants were removed before they shed any pollen. (Fig. 107.) Seed from the best Ferrara plants was saved, and this has been grown and selected at the experiment station at Madison, Wis. The cross was made for the purpose of combining the earliness and smaller diameter of stalks of the Italian hemp with the greater height and longer internodes of Kymington. This result has been achieved after many years of selection to eliminate diverse types from the progeny of the cross. This Ferramington has been tried in Wisconsin, where it gave a very good crop nearly two weeks earlier than the main hemp harvest. It has also been tried near Bologna, Italy, where it produced fiber fully equal in quality to that of the Ferrara hemp grown in the same field, and about 1 foot longer.”

The webbed leaf mutation seems to have been imported to North America from Italy within some of the Ferrara seeds. Roberto Savelli found the mutation in the Ferrara hemp in Italy, and having read about Dewey’s findings, had him send webbed Ferramington seeds so that he could compare the plants. He concluded that the mutation was the same, which is known in Italy as the “pinnatifidofilla” trait. Another leaf mutation which travelled to America was the simple leaf trait, known as “monofilla”, which also appeared in inbred Ferramington plants.

Luckily, the hemp traits have not been lost over the decades. They have been maintained in Italy, and a pinnatifidofilla strain named ‘Ermes’ may soon be used in commercial fiber and seed production.

The most well known strain with the trait is 'Ducksfoot,' bred by Wally Duck of Australia. Another well known strain is the Hawaiian Webbed Indica. If you are interested in these strains, a little history will be added soon.