Generic description
Lavandula L.
(Synonyms –
Stoechas
Mill.,
Fabricia
Adans.,
Chaetostachys
Benth.,
Sabaudia
Buscal.
and Muschl.,
Isinia
Rech. f.)
Shrubs, woody-based perennials or short-lived herbs; often aromatic, glabrous or with a vari-
able indumentum. Leaves variable in shape, entire or dissected, sessile or petiolate. Inflorescence
a congested terminal spike, occasionally with a coma, usually with distinct peduncle, simple
or branched, verticils either a many-flowered (3–9) cyme with minute bracteoles or a reduced
single-flowered cyme usually without bracteoles, subtended by persistent bracts variable in
form, which maybe opposite or spirally arranged on the inflorescence axis. Calyx persistent,
regular or two-lipped, upper with three-lobed,
the lower two-lobed,
equal in size or with the
posterior lip larger or modified into an appendage, eight-, thirteen- or fifteen-nerved, the nerves
in the lower sepals all borne to the apex. Corolla tube either just exceeding or up to 3
longer
6
Tim Upson
Flower
Bracteoles
Subtending bract
A bicincinnus cyme illustrating the branching pattern and position
of bracteoles and bracts
A single flowered cyme, with subtending bract
Figure 2.2
Diagrammatic representations of the structure of the many-flowered (bicicinnus) and
single-flowered cymes in
Lavandula
.
The taxonomy of the genus
Lavandula
L.
11
Key to sections
1
Cymes 3–9 flowered; nutlets with a basal scar only . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Cymes single-flowered; nutlets with a lateral scar . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
2
Leaves and calyx sessile, stigma capitate . . . . . . . . . . . . . . . . . . . . . . . . . . Section
Stoechas
Leaves and calyx with short stalk, stigma bilobed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3
Leaves with regular shallow dissections, corolla lobes subequal in size,
corolla tube just exerted from calyx, calyx appendage
c
. 1.5
width
of the calyx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section
Dentatae
Leaves simple and entire, corolla lobes differing in size, corolla
tube
c
. 2
length of the calyx, calyx appendage the same width as
the calyx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section
Lavandula
4
Leaves ovate lanceolate in outline, dissected or lobed; calyx zygomorphic (bilaterally
symmetrical);
corolla violet blue or white, strongly zygomorphic . . . . . . . . . . . . . . . . . . 5
Leaves linear and simple, calyx regular and lobes all equal; corolla yellow . . . .
L. atriplicifolia/
brown in colour, with equal lobes, star shaped . . . . . . . . . . . . . . . . . . . . . . . . .
L. erythrae
5
Cymes and bracts arranged in an opposite and decussate
fashion, spike 4-seriate (quadrate) to biseriate in shape . . . . . . . . . . . . Section
Pterostoechas
Cymes and bracts arranged in an alternate, spiral fashion.
Spike cylindrical or head like (capitate) in shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6
Spikes elongated, leaves pinnatifid or bipinnatisect, bracts ovate spinescent . . . . . . . . . . 7
Spike capitate, leaves lobed, bracts with orbicular wings . . . . . . . . . . . . . . . .
L. hasikensis
7
Leaves predominantly pinnatifid to bipinnatisect, suffruticose
shrubs, lateral scar on nutlets
c
. 0.25
the length of nutlet. Lower
corolla lip about the same size as lateral corolla lobes . . . . . . . . . . . . . . . Section
Subnudae
Leaves very distinctly bipinnatisect, plant herbaceous,
lateral
scar on nutlets
c
. 0.75
length of nutlet. Lower corolla lip
larger than lateral lobes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section
Chaetostachys
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