Leucas lavandulifolia Sm.

Global description

Leucas lavandulifolia is an herbaceous plant, generally branched, entirely pubescent, up to 1 m high. The leaves are opposite, simple, short-stalked, with elongated almost linear lamina, pointed at apex, margin entire or slightly serrated. The white flowers are grouped in globular whorls at ends of stems and branches. The fruit is an ovoid achene with 3 angles, brownish-black in color.
 
Cotyledons
 
The cotyledons are petiolate, 2.5 to 3.5 mm long, covered with a dense pubescence. The lamina (6 mm long and 5 mm wide) broadly oval, obtuse base, to weakly emarginate apex, pubescent, marked with a distinct midrib. The epicotyl has an oval to quadrangular cross-section.
 
First leaves
 
The first leaves are simple, opposite, carried by a stalk, 2 mm long, and pubescent. The lamina (10 to 11 mm long and 3 to 4 mm wide) elliptical to narrowly elliptical, attenuated base, rounded end, is pubescent on two sides and on the margin. The margin is slightly serrated. Venation is pinnate.
 
Growth habit
 
Often branched herbaceous plant, covered with a gray pubescence, measuring 20 cm to 1 m high.
 
Underground System
 
Taproot.
 
Stem
 
Stem and branches are in quadrangular section and pubescent.
 
Leaf
 
The leaves are simple and opposite, pubescent. The petiole is, at the most, 5 mm long. The leaf blade is closely elliptical to oval or nearly linear, attenuated at base, apex pointed, margin entire or slightly serrated. It measures 2.5 to 8 cm long and 0.4 to 1.5 cm wide.
 
Inflorescence
 
The flowers are grouped in whorls of 1.5 to 2 cm in diameter at the top of the stems and branches. The flowers, sessile, are underpinned by bracts linear, pubescent, 3 to 5 mm long.
 
Flower
 
The calyx (6-7 mm long) is pubescent both outside and inside. Its opening is oblique, framed by 8-10 tines, the upper are the larger, the lower are small and thorny. The corolla, white in colour, measures 10 to 15 mm. The tube (9 mm long) is pubescent on the outside near the opening. It is has a ring of hairs inside, towards the middle. The upper lip (3 mm long) is oblong, covered with woolly hairs. The lower lip (4-5 mm long) obovate, with middle lobe larger than the lateral, is spread, covered with loose pubescence.
 
Fruit
 
The fruit is an achene, 2 to 3.5 mm long, oblong to obovoid, triangular section, 3 obtuse angles. It is blackish-brown in color with a pale base.

Origin

Leucas lavandulifolia is native to tropical and subtropical Asia (India, southern China and Malaysia).

Worldwide distribution

This species is present and naturalized in the islands of the southwestern Indian Ocean (Mauritius, Comoros, Madagascar, Reunion).
 

https://www.gbif.org/fr/species/7307152