LES LAVANDES ET L'APICULTURE DANS LE SUD-EST DE LA FRANCE

Abstract

The genus Lavandula is represented in France by three species, Lavandula latijolia V ILL ., L. vera D. C. and L. stoechas L., and by one hybrid which groups together a series of individuals differing considerably one from another under the name of a Lavandius ». These lavandins are the result of cross-pollination by insects and especially by bees carrying the pollen from L. vera to the stigmata of 1,. latifolia. The pollen of each species can be identified by its distinctive characteristics. In the three species the normal rate of pollen formation varies between 94 and 99 p. ioo, while in the lavaudins this oo. amounts to from 2 to 1 6 p. I The lavandins are closely enough related to L. 7 ,,era, but they have certain distinguishing ana- tomical characters : vigorous vegetation and absence of seed. The essential oils produced from the various cultivated types are different from, and more abundant than, those extracted from the true lavenders.Except that the lavandins have certain differences of vegetation and longer stems, both they the lavenders follow a very similar course of vegetativc development. The opening of the corollas on the spikes takes place on all the verticils at alnrost the same time and lasts for over a month in each cultivated a variety o. The daily flowering rhythm of the corollas is influenced by a number of different factors. among which temperature and atmospheric humidity are very important. Rain, taken as an isolated fac- tor, has a definite effect and sunshine also exerts positive action. Blossomiug is particularly abundant in the morning time. A corolla normally sucked by the bees fades in tW O to two and a half days, the secretion of nectar ceasing at the same time. If it is not visited by the bee, the flower will persist for 10 to 12 days. In the former case the flower produces on average i mg of sugar as compared with 2 mg in the latter. The honey-gathering bees will stimulate a permanent increase in the yield from the lavandins, whereas with the true iavanders this increase is only temporary and is followed by an important drop in the amount of essential oils which can be removed by steam extraction. Lavandin cultivation dates only from about 1925 , but today it covers larges areas in Provence, particularly in the Departments of the Basses-Alpes, ! aucluse and Dr6me. It may even have exteii- ded into Languedoc. Although lavandins are very important nectar-bearing plants, their pollen has no nutritive value to bees and is not gathered by them. The older flowers produce a more concentrated nectar. The nectar contains only three sugars : glucose, laevulose and sucrose. Sucrose reaches 54 p. 100 of the dry matter.