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LAVENDER
Lavandula spp., family Labiatae

Lavender is grown primarily for its aromatic oil. Cultivation is in southeastern England, and in the Mediterranean area, especially in southern France. Barbier (1963) stated that the genus Lavandula is represented in France by three species: L. latifolia Medic., L. stoechas L., and L. vera DC., and by a series of individuals differing considerably from one another and referred to as "lavandins." Lavender should be cut for harvest at the last stage of blossoming (Barbier 1958a).

Plant:

Lavender plants are shrubs about 3 feet tall, with l/2 to 2-inch linear leaves on numerous stems and branches. The branches terminate in 2- to 10-flowered whorls on tapering spikes.

Inflorescence:

The opening of the florets on a spike lasts for over a month. Opening occurs primarily in the morning. The stamens and style of a flower are enclosed in the bilabiate corolla. Nectar is produced in the corolla at the base of the ovary. At flower opening, the anthers unfold exposing pollen on their upper surfaces. The stigma, however, remains in the immature stage, not even reaching to the middle of the corolla tube, so that insects removing pollen cannot pollinate it. Later, the stamens fade, and the style elongates to 1 l/2 times its original length. The stigmatic lobes then diverge and are receptive to pollen, but the pollen from the same flower has already been removed by insects. If the corolla is visited by bees, it fades in 2 to 2 l/2 days; but if not visited, it will persist 10 to 12 days (Knuth 1909*, p. 246, Barbier 1963).

Pollination Requirements:

Pollen is shed and removed from the anthers before the stigma is receptive, but the stigma may elongate sufficiently to make contact with other pollen-laden anthers and selfing may result (Knuth 1909*, p. 246). However, Barbier (1963) stated that bee visits cause an increase of 16 to 20 percent in yield of essential oils of lavandins, and a temporary increase followed by a heavy drop in yield of the lavenders, the latter being linked to the ripening of the seed. Barbier (1958a) deduced that a hormone in the pollen causes the withering and seed initiation, which, "since the lavender is sterile," leads indirectly to the formation of more oil.

Pollinators:

Honey bees freely visit flowers of lavender and are the most effective pollinators. Barbier (1958b) considered the benefits to bees and lavender reciprocal; lavender is an excellent source of high quality honey, and through its foraging activity the bee induces a noticeable increase in the yield of oil.

Pollination Recommendations and Practices:

Barbier (1958c) stated that although both beekeeper and lavender grower benefit from bee activity on the blossom, it is to the lavender grower's benefit to attract bees into the plantings.

LITERATURE CITED:

BARBIER, E. C.
1958a. [RELATIONS BETWEEN THE FL0WER DEVELOPMENT OF LAVANDIN AND THE OIL PRODUCED.] Acad. d'Agr. de France, Compt. Rend. 44(12): 616 - 622. [In French.] AA-251/61.

______ 1958b. [THE ROLE OF THE BEE IN THE PRODUCTION OF OIL OF LAVENDER.] In 17th Internatl. Apic. Cong. Proc., Rome, p. 14. [In French.] AA-458/58.

______ 1958c. [RECIPROCAL ADVANTAGES OF A NATURAL ASSOCIATION BETWEEN LAVENDER AND THE BEE. ] Acad. d'Agr. de France, Compt. Rend. 44(12): 628-633. [In French.] AA-238/61.

______ 1963. [LAVENDERS AND APICULTURE IN THE SOUTHEAST OF FRANCE.] Ann. de l'Abeille 6(2): 85-158. [In French, English summary.]

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