Three methods for evaluating differences in root tolerance to soil acidity were tested on tanier (Xanthosoma spp.) varieties Alela and Vinola. In each method, tanier root growth responded significantly to calcium hydroxide application to a Maricao clay initially at 68% A1 saturation, in the most efficient method, sections of tanier corms were grown 5 weeks in Pro-Mix in 8.7-cm diameter plastic cups. These "inserts" were removed from the plastic cups and placed In the center of 20-cm pots in contact with 3 pie-shaped sections of soil which had exchangeable aluminum contents of 10, 4, and 0 meq/100g prepared by the addition of 0, 6.7 or 20 meq/100g lime, respectively. The soils were in separate plastic bags open in the center so that roots from the insert could grow into any or all soils. In the other two methods, either inserts or plants grown in sand beds were placed in pots treated with only one lime level each. After 18 days of growth, the roots which had penetrated into each soil were cut off and separated by size. Root growth was greatest in the soil treatment with 6.7 meq/100 g lime, and least in the treatments with 0 or 20 meq/100 g lime. Diminished growth in the latter was apparently due to over-liming since pH reached 6.9. There was no clear difference in lime response between the two varieties tested. Coefficients of variation ranged from 34 to 73%.