. The Canadian field-naturalist. Natural history. 44 The Canadian Field-Naturalist Vol. 84 gravel banks. The root systems of Saponaria officinalis and Silene cucubaliis are often torn apart during floods. We have observed that the resulting fragments are transported downstream on occasion. We have also observed regrowth from such fragments of Saponaria officinalis. Periodic flooding does occur during other sea- sons but we have observed little disturbance of the gravel or the vegetation except when ice is present. The experimental material was not placed on the gravel banks because conditions
. The Canadian field-naturalist. Natural history. 44 The Canadian Field-Naturalist Vol. 84 gravel banks. The root systems of Saponaria officinalis and Silene cucubaliis are often torn apart during floods. We have observed that the resulting fragments are transported downstream on occasion. We have also observed regrowth from such fragments of Saponaria officinalis. Periodic flooding does occur during other sea- sons but we have observed little disturbance of the gravel or the vegetation except when ice is present. The experimental material was not placed on the gravel banks because conditions there lack uniformity and because summer drought might have prevented regeneration which would other- wise have occurred. Also, many fragments would probably have been washed away during the winter. The object of this work was to evalu- ate the potential for regeneration of under- ground portions of these two species. Materials and Methods Every month from May until September, 1967, the rhizome systems of five healthy plants of Saponaria officinalis were carefully excavated from a gravel bank on the campus of the Uni- versity of Western Ontario. For each plant the three largest rhizomes were used. One was cut into cm lengths, another into 5 cm lengths and the third into cm lengths. The number of fragments of each size varied according to the size of the original rootstock (Table 1). The cuttings were laid horizontally on a 3 cm depth of silica sand in a wooden seed flat and covered with a further 1 cm depth of sand. They were then watered thoroughly and the boxes were set outside in partial shade in a completely ran- domized pattern. Regeneration was noted when a shoot emerged from the sand. In both July and August, 1967, three robust plants of Silene cucubalus were carefully exca- vated from the gravel banks in Gibbons Park, London (Figure 1). The region of stem arising from the crown but below the soil surface was used in these studies; three from each plant were sele
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