A DESCRIPTION OF TUMORS ON IPOMOEA TUBA FROM THE A-BOMB TEST SITES ON ENIWETOK ATOLL
Appendix to Radicbiological Survey of Bikini,
Eniwetok, and Likiep Atolls--~July-August 1949
By Susann F. Biddulph and Orlin Biddulph
Tumors on plants of Ipomoea tuba were found on Engebi Island during the
radiobiological survey of July and August, 1949.
At this time (17 months from
the test shot on Engebi Island) many of the Ipomoea tuba plants located in an
area 400 to 600 yards from the bomb crater showed tumorous growths of various
sizese
The tumorous plants were found in disjunct areas of grass which had
not been fully covered by the dense growth of Ipomoea which surrounded them
(Figure 1).
This species of Ipomoea is a vine with large heart-shaped leaves and a
stem which grows prostrate on the ground to a length of some ten meters (Figure 2).
The tumorous deformations on the plant varied from small warty out-growths
at the nodes on the basal portions of the stem (Figure 3) to huge, convoluted
tumorous masses completely covering a stem which had been reduced to only a few
centimeters in height.
The ability of the plants to recover from the deforma-
tion was indicated by the fact that the tumors were confined to the basal nodes
in the first case mentioned above, and that even in the most severe cases
normal leaves were occasionally produced from tumorous masses (Figure 4).
Morphological and physiological abnormalities were found in other plants
and on some of the other islands surveyed.
These were noted in the original
report by both Biddulph and St. John (30) and included
twisted stems and
leaves, reduced leaves, abnormal fruits, double flowers, color changes, etoe
So far as observed, Ipomoea tuba was the only plant to show tumorous growths.
Time and facilities did not permit a study of the tumors during the survey, but dried and preserved materials were brought back for study.
Since the problem of what causes abnormal plant growth and how it is
maintained is one of the most fundamental in biology, we have made a survey of
the literature on plant galls, or tumors, in an attempt to compare the tumors
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