The anatomy of a dehiscent berry

Berries, which are fleshy by definition, are usually dispersed by birds or other animals which by eating the fruit often condition the seeds ready for germination after they have passed through the digestive tract. Capsules, on the other hand, are dehiscent by definition, and the seeds are usually dry and dispersed by wind or the vibration of the infructescence. A dehiscent berry appears therefore to be a contradiction in terms. However, Ligustrum sempervirens (Oleaceae) of south-west China produces just such an anomalous berry. After flowering, fleshy blue-black berries typical of Ligustrum are developed. These remain on the plant throughout the winter and into the spring, gradually losing their fleshiness until they become rather dry and eventually dehisce, exposing the seeds ready for secondary dispersal. Mansfeld (1924) investigated the anatomy of the fruit in Ligustrum vulgare and described the endocarp as consisting of elongated and eventually lignified cells. Although he was aware that L. sempervirens is a special case, he was unable to investigate it due to lack of material. In this paper we present the comparative anatomy of the fruit of a plant of L. sempervirens growing at the Royal Botanic Gardens, Kew. Ligustrum sempervirens was first described as a species of Syringa by Franchet (1886), based on a fruiting specimen collected in south-west China by Delavay. Lingelsheim (1920) transferred it to Lzgustrum after rejecting it as a species of the genus Syringa, which he had revised, and Mansfeld (1924) accepted this and included it in his revision of Ligustrum. However, W. W. Smith (1916), noting its anomalous fruit, had proposed the monotypic genus Parasyringa to accommodate it. In this classification he was followed by Stapf (1933), but apart from the fact that the fruit eventually dehisces, it is in other respects a typical Ligustrum, and is now generally included in that genus, constituting its own monotypic Section Sarcocarpion (Franch.) Mansfeld.