Verbena brasiliensis Vell.

Global description

Verbena brasiliensis is an annual to shortly perennial herb, erect or prostrate then erect, branched, reaching up to 2 m high. The stem is quadrangular, furrowed, glabrous or slightly scabrous, especially on corners. The leaves are simple, opposite and decussate, with short petioles, and with entire narrowly oval to oblong blade and having wedged base and finely serrated margin. The flowers are grouped in terminal inflorescences branched in panicles, carrying short and compact spikes, 1 to 4 cm long, small flowers in tube with five lobes pale lilac or pale blue in colour.
 
Cotyledons
 
Cotyledons held by a petiole, 5 mm long. The lamina is oval, 8 mm long and 6.5 mm wide, at the top corner, attenuate base corner, light green.
 
First leaves
 
First leaves simple, opposite, short-stalked with oval elliptical blade, 15 to 18 mm long and 10 to 12 mm wide, distinctly veined, margin entire at first and then finely serrated as from the second pair.
 
General habit
 
Herb, erect or prostrate and erect, branched, up to 2 m height.
 
Underground system
 
The plant has a taproot system.
 
Stem
 
Stem is quadrangular, solid, rigid, erect, slightly furrowed on two opposite faces, glabrous to slightly scabrous on angles. It quickly branches as a chandelier.
 
Leaf
 
Leaves are simple, opposite, decussate. The blade has a short petiole and is narrowly oblong oval to linear, 2.5 to 8.5 cm long and 0.75 to 5 cm wide. The base is attenuated in vertex, the apex is acute. The margin is serrated. Both sides are glabrous.
 
Inflorescence
 
The inflorescence consists of short and compact spikes, 1 to 4 cm long, grouped in panicles more or less loose.
 
Flower
 
The flower is underpinned by a leafy bract, shorter than the calyx, oblong to very narrowly oval, acuminate, green or purple, with clear midrib. The calyx, 2 to 2.5 mm long, is fused into a quadrangular tube. It has a dense glandular pubescence; it is sub-truncate at the top, surmounted by four sharp tines of 0.5 mm. The corolla is fused into a cylindrical tube, 3 to 4 mm in length, ending in 5 spread lobes, 3 to 5 mm in diameter. It is pale blue or pale lilac in color.
 
Fruit

Dry fruit, surrounded by the calyx, disintegrating into four nucules which  are oblong to linear, trigonal, reddish brown, shiny, rough, cross-linked, 1.8 to 2 mm long and 0.5 to 0.7 mm wide.

https://www.gbif.org/fr/species/2925518