Lavandula
angustifolia Mill.
Standardized Common
Name: English Lavender
Other Common Names: Common Lavender,
Continental Lavender, True Lavender
Family: Lamiaceae (Labiatae)
Taxonomy: Lavandula
includes about 30 species, found primarily in warm habitats in the Old World. Seven
are native to southern or Mediterranean Europe, including L. angustifolia.
Some commonly seen synonyms for this
species are L. officinalis Chaix., L. vera DC., and L. spica L. (in part). Lavandula
spica, as used in pharmaceutical
literature, usually referred not to English lavender but to L. latifolia Medik. (Spike Lavender); since the meaning of L. spica is now wholly ambiguous, that name has been formally rejected and
should not be used for either species. The common name “English lavender” is
frequently also used for Lavandin (Dutch Lavender), L. ×intermedia Emeric ex Lois., which is a hybrid of L. angustifolia and L. latifolia. Personal observations by [TK: Author]
indicate that almost all commercial English Lavender in the United States and
United Kingdom is of hybrid origin; the broader definition of English Lavender
as including Lavandin should perhaps be accepted in practice as conforming to
established custom.
Description: Perennial shrub to
>1 m tall. Stems branching, crooked, quadrangular, woolly-pubescent with
stellate hairs. Leaves opposite, sessile, lanceolate to oblanceolate or linear,
2–5 cm long, green to grey, pubescent with stellate hairs; margins revolute. Inflorescence
a loose terminal spike of 6–10–flowered verticillasters, 2–8 cm long,
bracteate, with the lowest whorl separated from the others; bracts (1–)3–8 mm
long, rhomboid, acuminate; bracteoles subtending individual flowers tiny,
scarious and linear, or absent. Calyx tubular, narrowing near the mouth, 4–7 mm
long, 13-veined, bluish-grey to purple, pubescent with large stellate hairs and
glands; teeth 5, small, the upper tooth with an obcordate appendage. Corolla
bilabiate, tubular, 10–12 mm long, deep blue to purple in upper portion,
pubescent; upper lip 2-lobed, lower lip 3-lobed, upper lobes somewhat larger,
rounded; lower portion of tube narrowed. Stamens 4, 2 longer, 2 shorter, the
filaments attached basally to the corolla tube. Style gynobasic; ovary 4-lobed.
Fruit 4 nutlets.
Parts
in Commerce:
Flowers or flowering spikes
Identification:
Bracts
- Bracts rhomboidal to ovate with an acuminate tip and membranous,
normally not linear and leaflike
- Bracteoles beneath individual flowers absent or membranous, linear,
<2 mm long (or 2–6 mm long, sometimes branching, in plants of hybrid
ancestry)
Calyx
- Tubular, narrowed at mouth, 4–7 mm long
- Bluish to purplish over much of length, with conspicuous branched
hairs
- With 13 veins, not 8 or 15
- With 5 small teeth, upper tooth largest and sometimes with visible
appendage
Corolla
- Bilabiate, tubular, widening above, with equal lobes
- Blue to purple; generally not deep purple
- 10–12 mm long
- Odor pleasant, characteristic
Adulterants: Most of the seven European species of Lavandula are of some
commercial value. All but L. latifolia (Spike Lavender) and L. ×intermedia (Lavandin) can be distinguished without
difficulty by floral characters. Spike lavender has corollas that are only 8–10
mm long, and the calyx is grayish, with purple color only at the tips. The
bracts are linear rather than rhomboid, but the bracteoles subtending
individual flowers are 2–6 mm long and sometimes branched. Some
cultivars of L. angustifolia may resemble L. latifolia. Lavandin,
the hybrid of the two species, is sterile and is propagated vegetatively. It is
generally intermediate in form, often having ovate-rhombic bracts like L.
angustifolia but relatively large bracteoles like L. latifolia. As
noted above, the sale of hybrid material under the name of English Lavender has
become customary, and if it has suitable chemistry (and hence aroma, etc.),
there seems to be no reason to object.
References:
Applequist WL. Proposal to reject the name Lavandula
spica L. (Lamiaceae). Taxon. 2001;50:1213–1214. [For
nomenclature.]
Guinea E. Lavandula. In: Tutin et al., vol.
3. 1972:187–188.
McNaughton V. Lavender: the Grower’s Guide. Portland,
OR: Timber Press; 2000.
Tucker AO. The correct name of lavandin and its
cultivars (Labiatae). Baileya. 1981;21:131–133. [For nomenclature.]
Figure 37: a–b, Lavandula angustifolia flowers and calyx
with large hairs not shown; c, L.
latifolia.
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