Many publications have described eccentric growth (non-uniform growth of secondary xylem) caused by the death of the vascular cambium. The purpose of the present research was to determine if roots of Purshia tridentata (Pursh) DC exhibited eccentric growth. Eccentric growth in roots of P. tridentata was studied with three sequential segments 8 mm apart for 5 roots. Data of the three sequential segments provided a method to determine changes in eccentric growth along roots. Each wood segment was subdivided into ten sectors of 36° each. The areas of xylem rings within each sector from year to year within each segment were used to determine vascular cambium activity. For more than 95% of all rings, areas of at least one sector were significantly different from areas of other sectors for all roots. Except for one first- and second year xylem rings, all other xylem sectors were eccentric. Among sequential 8 mm root segments more than one-half of segment pairs were statistically different. The above results demonstrate that root eccentricities were very localized both within individual segments (sectors within each segment) and along roots (from one segment to the next segment). In summary, the five root samples were eccentric and showed very similar ring patterns, growth rates and eccentricity patterns. To our knowledge this is the first publication to show eccentric growth of roots similar to eccentric growth of stems.

许多出版物都描述了由血管形成层的死亡引起的偏心生长（次生木质部的不均匀生长）。本研究的目的是确定紫潮DC的根是否表现出偏心生长。三角假单胞菌根的离心生长用三个相距8 mm的连续节段研究5个根。三个连续段的数据提供了一种确定沿根部偏心生长变化的方法。每个木段细分为十个36°的扇形区。在每个区段中逐年逐年的木质部环的面积用于确定血管形成层的活性。对于所有环中超过95％的环，至少一个扇区的面积与所有根的其他扇区的面积显着不同。除了第一年和第二年的木质部环，其他所有木质部部门都是偏心的。在连续的8 mm根段中，超过一半的段对在统计学上是不同的。以上结果表明，根部偏心率在单个段（每个段中的扇区）内以及沿根（从一个段到下一个段）都非常局部化。总之，这五个根样品是偏心的，并且显示出非常相似的环型，生长速率和偏心型。据我们所知，这是第一本显示根部偏心生长类似于茎部偏心生长的出版物。