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The allometry of axis length, diameter, and taper is described for the trunk, rachis, and rachilla of nonbranching ramets of Aralia spinosa. Significant log-linear relationships were found between length and diameter for all axis categories, and in all cases, scaling was negatively allometric. Linear models best described the relationship between length and diameter for the rachis and rachilla, while a quadratic model best described this relationship for the trunk. During the trunk-building stage, the safety factors for trunk height were size dependent, with larger trunks exceeding their predicted critical buckling height. Taper was described by a linear relationship between diameter and position along the axis for all axis categories. All rachises and rachillas sampled exhibited taper along the length of the axis, however, only 51% of the trunks showed continuous taper. The trunk was less tapered than the rachis, but no differences in taper were found between the trunk and the rachilla, or the rachis and the rachilla. In unbranched ramets the large bipinnately compound leaves occupy the space normally occupied by lateral branches. We suggest that the rachis and rachilla are functionally equivalent to branches, that is, acting as axes of exploration and exploitation of the environment.

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Quantitative architectural variation was investigated among the axes of Thuja occidentalis. Forty axes of each axis order were randomly sampled and for each axis: length, excurrency index, basal diameter, number of daughter axes, number of basal reiterated axes, dorsiventrality index, and percentage of length partitioned into photosynthetic (bearing green leaves) and nonphotosynthetic (nongreen) components was determined. The crown exhibited six axis orders. Both axis length and basal diameter declined with increasing axis order, and crown form was excurrent. The number of daughter axes was highest on axis order 1 (trunk) and lowest on axis order 5. Axis orders 2 through 4 had a similar number of daughter axes. The frame of the tree was composed of axis orders 1 and 2. These axes were radially symmetrical in midpoint cross section, exhibited indeterminate growth, and only a small percentage of their length was devoted to photosynthetic tissue. Axis orders 3 through 6, taken together, had many characteristics of compound leaves. They were dorsiventrally flattened, exhibited determinate growth (axis terminated by a cone or abscised), and the majority of their length was devoted to photosynthetic tissue. In autumn these axes were often abscised as a unit. Both male and female cones were located terminally on axis orders through 6, with 82.7% of male cones occurring on axis order 6, and 86.0% of female cones occurring on axis order 5. The architectural unit of T. occidentalis resembled that of Thuja plicata. Attims' model most closely resembles the architectural pattern of these two species. Key words: Thuja occidentalis, eastern white cedar, architecture.