Proplesis. - It frequently happens that branches or whole plants are suddenly defoliated in summer, - e.g. by caterpillars or other insects - at a time when considerable stores of reserves had already been accumulated during the period of active assimilation. In such cases the axillary buds, which would normally have passed into a dormant condition over the winter had the leaves lived till the autumn-fall, suddenly shoot out into proleptic shoots (also termed Lammas shoots), and re-clothe the tree with foliage. The wood of the year in which this occurs may exhibit a double annual ring, and the vigour of the tree is likely to suffer in the following season and no fruit be matured.

Proleptic branches may also be due to the shooting out of accessory buds - i.e. extra buds found in or near the leaf-axils of many plants, such as Willow, Maples, Cercis, Robinia, Syringa, Aristolochia, etc. - which do not normally come to anything, or do so only if a surplus of food materials is provided.