The writer (1, 2) has recently pnblished certain results of extensive experiments relating to gall formation in host stems following haustorial invasion by Cuscuta. Concurrent with these experiments certain host plants were allowed to grow in the greenhouse until flowers and fruits had been formed. Stems of Cuscuta Gronovii Willd., growing from adjacent host plants, twined of their own accord around developing pods of the garden pea, Pisum sativmn L. These plants were left undisturbed until the pods were matured. early in the summer of 1936. Three pods of the garden pea were affected; two on one host, a third on another plant. On one pod the dodder stem made only a single coil but two complete coils encircled each of the other two pods. Haustoria penetrated the pericarp of each pod at points where the close, almost horizontal, coils of the cloclder stem pressed tightly enough to stimulate the formation of these organs. Enlargement of the pericarp following haustorial entry formed spirally ascending ridges on each affected pod. A pod bearing two coils of the dodder stern and showing the swelling of this fruit due to haustorial entry is shown in figure 1. This drawing, made directly from a photograph, shows the type of swelling formed on each affected pea pod. Other pods on the same plants were not affected by the dodder, simply because the parasite stems did not happen to come in contact with them. The swollen areas of the pericarp consisted mainly of parenchyma cells, somewhat larger in size than those of an unaffected region of the same pod. The seeds in the fruit directly affected by haustorial entry were noticeably smaller than those in an unaffected part of the pod. All seeds in the parasitized fruits were smaller than those in dodder-free pods.
Proceedings of the Iowa Academy of Science
©1938 Iowa Academy of Science, Inc.
Dean, Henry Lee
"Fruit Hypertrophy Caused by Cuscuta,"
Proceedings of the Iowa Academy of Science, 45(1), 95-97.
Available at: https://scholarworks.uni.edu/pias/vol45/iss1/13