Dimensions of Root Caps and Columella Tissues of Primary Roots of Ricinus communis Characterized by Differing Degrees of Graviresponsiveness

Primary roots of Ricinus communis having large caps and columellatissues are more graviresponsive than primary roots with smallcaps and columella tissues. The increased graviresponsivenessof roots with larger caps correlates positively with their columellatissues having larger length: width ratios than less graviresponsiveroots having smaller caps. Roots with wider tips typically aremore graviresponsive and have more extensive columellas thanroots with thinner tips. However, the size of the columellatissue correlates positively with graviresponsiveness, irrespectiveof the width of the root tip. These results indicate that differingdimensions of the columella tissue may be the basis for thediffering graviresponses of primary roots of R. communis. Root gravitropism, columella, root cap, primary root, Ricinus communis, castor bean