Click for previous Image Image 1 of 2 Tradescantia x Spiderwort

Tradescantia x 'KU9'


Plant Type:


Tradescantia KU9 (ex: Kyoto University) – A very dear friend supplied us with this utilitarian form of Spiderwort bred to be a radiation monitor. It is quite rare, and with more and more talk of new nuclear plants as a “green” alternative to fossil fuels perhaps KU9 should become less rare. The following is from a May/June 1979 report by the awarded environmental journalist, Karl Grossman, who in 1979 was a faculty member of the State University of New York. This is how it works…

The spiderwort is considered “the most excellent test system ever known for low-level radiation,” by Japanese geneticist Sadao Ichikawa. Dr. Ichikawa was on the team at Brookhaven National Laboratory on Long Island that developed the monitoring system in the late 1960s.

Radiation turns blue cells of the stamen hairs of the spiderwort pink. The increase in pink cells is proportional to the dose of radiation received, even if the doses are extremely low. KU7 is a variety of Tradescantia ohiensis, and clone KU9 is a hybrid of T. paludosa and T. ohiensis.

The color change can be observed most efficiently 12 or 13 days after the plants’ exposure to radiation. The stamens can be examined under a low-level microscope and the number of pink cells counted.

The article is quite long and goes into some detail. We do know that exposure to even low-level radiation can cause cancer, leukemia, infant mortality and genetic injury in humans and animals though the incubation period is sometimes many years, even decades.

Back to the plant: segmented stems with grassy blades support blue 3-petaled flowers (preferably without pink stamens!) We’re not certain of the hardiness though it survived tough conditions for a few decades on Long Island USDA zone 6 (probably considered zone 7 now). T. ohiensis occurs naturally up into Canada so we assume it hardy from zone 4 to probably 9. T. paludosa, however, is a Deep South species though that does not necessarily indicate that it may not be northern hardy into zone 6 or even 5… and the hybrid genetic mix, well… we cannot say at this time where the hardiness may cut off. So, please take our hardiness designations with a grain of salt. KU9 is a quick colonizer. These are sold as pot grown divisions. In our Autumn shipping window 'KU9' will be sent cut back.


12-18 In




(4?)5 to 9(10?)
What is my hardiness zone?
Item Description Price  
TRADKU9 Tracescantia x v. KU9 (3.5 inch Square Press Fit Pot Extra Deep – 1.52 pints / 720 ml.) $12.00

Characteristics and Attributes for Tradescantia x 'KU9'

Season of Interest (Flowering)

  • Spring / Summer

Season of Interest (Foliage)

  • Spring / Summer / into Autumn

Nature Attraction

  • Deer Resistant


  • Morning Sun / Afternoon Shade
  • Full Sun


  • Border
  • Drought Tolerant
  • Medicinal / Herbal
  • Ground Cover
  • Massing

Growth Rate in the Garden

  • Rapid


  • Adaptable


  • Garden Origin

Propagated By

  • Division