Oenothera rosea Aiton

Code

OEORO

Growth form

Broadleaf

Biological cycle

perennial

Habitat

terrestrial

Global description
 
Oenothera rosea is an herbaceous plant with annual aerial stems and perennial woody stump from which several stems emerge, slightly or not branched. The leaves are simple, alternate, and petiolate. The blade is oval, becoming narrow elliptical in the upper part of the plant. The apex is acute; the base is wedge-shaped or reduced to acute. The margin has few scattered tines, especially towards the base. The flowers are solitary on the axils of the terminal leaves. They are pedicellate. The flower has a club shape inferior ovary, surmounted by a floral tube prolonged by 4 free sepals narrowly triangular and reflected, then deciduous and 4 petals largely obovate, pink or purplish red in color. The fruit is an elongated capsule in the form of a dehiscent club and more or less winged at the top.
 
General habit
 
Oenothera rosea is an erect herbaceous plant emerging from a woody perennial stump. Several ascending stems start from the base. They are slightly or not branched.
 
Underground system
 
The underground apparatus consists of a globular ligneous stump from which roots and leafy stems emerge.
 
Stem
 
The stem is cylindrical, full, slender, 20 to 100 cm high. It is more or less covered with a very thin, short, stiff and suppressed pubescence.
 
Leaf
 
The leaves are simple, alternate, held by a petiole, 1 to 2 cm, without stipule at the base. The lamina is oval to narrowly elliptical. It measures 2 to 5 cm long, gradually becoming smaller towards the top of the plant. The base is wedged or acute, the apex is acute. The margin is entire, or with some scattered tines becoming coarser towards the base. Both faces are glabrous.
 
Flower
 
The flowers are solitary in the axils of the terminal leaves. They open at dawn. They are carried by a peduncle 5 to 20 mm long. At the base of the flower is an elongated inferior ovary in the form of a club. It is surmounted by a floral tube, 4 to 8 mm long, slender, very finely pubescent at the top of which are 4 green free sepals, narrowly oval triangular 5 to 8 mm long. The sepals are rapidly reflected, then deciduous. The 4 free petals are largely obovate, 5-10 mm long and pink or purplish red, with darker veins. The 8 stamens are subequal, with filament 4 to 6 mm long and anterior yellow biloculars. The style is 6-10 mm long and ends with a 4-lobed stigma.
 
Fruit
 
The fruit is a narrow obovate capsule, narrow at the base, 8 to 10 mm long and 3 to 4 mm wide, opening at the top in 4 valves at maturity. It is more or less winged at the apex at the top and traversed by 8 longitudinal ribs.
 
Seed
 
The seeds are numerous, oblong to obovoid, 0.6 mm long, brown in color.

Oenothera rosea is a species with annual stem and perennial stump. It multiplies by seeds.

Oenothera rosea is a species introduced in Mauritius and Reunion which is found in the upper parts of these islands as a ruderal species on the roadside and on slopes.
Madagascar: Introduced and naturalized in Antananarivo in the garden of Tsimbazaza, but undoubtedly also present in other situations between 1000 and 1400 m of altitude.

Origin
 
Oenothera rosea is native to South America (Peru), Central America (Mexico) and northwestern USA.
 
Worldwide Distribution
 
This species has been introduced in many temperate countries (France) and in tropical regions (Madagascar, La Réunion, Mauritius, China, south-west Asia, Australia).

Madagascar: Oenothera rosea is not reported as a weed of crops.
Mauritius: this species is found as a weed of crops.
Reunion: this species is present in Cilaos along roadsides and in crops but is not a problem.

Images d'herbiers ReCOLNAT : https://explore.recolnat.org/search/botanique/simplequery=oenothera%2520rosea