Lavandula spica L., nomen amhiguum

Under the name L. spica, still commonly used in gardens, Linnaeus described two lavenders that almost all other botanists, before and since his time, have regarded as quite distinct species. These are the narrow-leaved, broad-bracted lavender L. angustifolia Mill, (the ‘true’ lavender), and the broad-leaved, narrow-bracted lavender L. latifolia (L. f.) Med., commonly known as ‘spike’. This was not an unusual situation, and no confusion would have resulted had there been agreement among botanists as to which of the two species should retain the name L. spica. Unfortunately, Linnaeus had chosen a misleading epithet for his compound species. At the time when he described it in his Species Plantarum (1753), the epithet spica was in use for both the lavenders concerned or at least was not yet of fixed meaning (Miller used it first for L. angustifolia, later for L. latifolia). But by the end of the century it seems to have become restricted to the broad-leaved lavender, whose oil was known as ‘oleum spicae’. So it is not surprising that many botanists, in the absence of any other clues as to the identity of the typical L. spica, used this name for the spike lavender. The ‘other’ lavender therefore needed a new name and in the event it received three – L. angustifolia Mill., L. officinalis Chaix, and L. vera DC. Other botanists of repute, however, considered that the typical L. spica was the narrow-leaved ‘true’ lavender, which Linnaeus described first, immediately under the heading. According to this interpretation it was the broad-leaved lavender (‘spike’) that had to be separated from L. spica, and for it the pre-Linnaean name L. latifolia was taken up.

Thus it came about that one name – L. spica – was used almost equally by botanists for two distinct species. In 1932, Miss M. L. Green proposed that L. spica should be discarded as a nomen ambiguum, in accordance with the rule that a name must be rejected if it has become a persistent source of confusion, and in the International Code of Botanical Nomenclature (ed. 1966), Art. 69, L. spica is actually cited as an example of such a name. The two species involved in the confusion will be found in the present work under the names L. angustifolia and L. latifolia.

In gardens, the name L. spica has been used for horticultural varieties some of which are near to L. angustifolia (syn. L. spica of some botanists; L. officinalis Chaix; L. vera DC.), while others are clearly hybrids between L. angustifolia and L. latifolia (L. spica sensu de Candolle, Bentham et al). See further under these species.

The misuse of the name L. vera in gardens seems to be a result of the ambiguity of the name L. spica. It is often used at the present time for the so-called Dutch lavenders, which are near to L. latifolia and therefore far removed from L. vera DC. It is easy to see that this mistake could have arisen through wrongly equating L. spica Hort. with L. spica sensu DC., thus bringing de Candolle’s other species, L. vera, into equivalence with L. latifolia or hybrids near to it.

From the Supplement (Vol. V)

In the second paragraph on page 536 mention was made of Article 69 of the 1966 edition of the ICBN, which provided for the rejection of such confused names as L. spica Linnaeus. This article, as then worded, has been deleted, to be replaced by a new Article 69 which defines a nomen ambiguum more narrowly and in a manner that would no longer justify the rejection of L. spica (or of many other names of uncertain application). No doubt it will be decided in due course whether the name should be used for L. angustifolia or for L. latifolia. For another alternative, see the remarks in this supplement under Fraxinus angustifolia, with reference to F. rotundifolia Mill.