Recent studies by a Japanese scientist indicate that the spiderwort, a common, roadside wildflower that is already known as an effective monitor of pesti eldest auto exhausts and sulfur dioxides, could also be an ultra‐sensitive monitor of ionizing radiation.

He has reported finding that in certain artificially raised or cloned species of the plant, cells of hairs on the pollen‐bearing stamens mutate from blue to pink when exposed to as little as 150 millirems of radiation. Radioactive isotopes sometimes emitted by nuclear activities give off radiation at about that level. The average person receives about 100 millirems a year from natural baCkground, and Federal guidelines urge that the limit for exposure to man‐made radiation sources be no more than 170 millirems a year for the general public.

The results of the studies by Dr. Sadao Ichikawa, geneticist at Saitama University in Japan, are published in the current issue of Garden, the monthly journal of the New York Botanical Garden, and in a, recent issue of the Bulletin of the Brookhaven National Laboratory in Long Island, where Dr. Ichikawa participated in spiderwort biomonitoring research.

Dr. Ichikawa, whose data was compiled in the United States, Japan and Europe, said he found the spiderwort a more reliable indicator of the effects of lowlevel radiation than the currently used mechanical counters such as the dosimeter. The latter instrument measures external exposure only which, he felt, was not a sufficiently meaningful measure for a living biological system. Some scientists say they doubt the spiderwort can detect the low levels of radiation that Dr. Ichikawa believes it can.