Genus Oenothera L.

L., Sp. Pl. ed. 1 (1953) 346; Gen. Pl. ed. 5 (1754) 163

Fam:   Onagraceae Juss.
Genus:   Oenothera L.
English Name: Evening primrose, Suncups, Sundrops


Annual, biennial or perennial grasses. Leaves consecutive, entire, toothed or divided. The flowers are regular, large, arranged mainly in a wide class. The hypanthium is long. Sepals 4, during flowering inverted backwards. Petals 4, large, yellow or rarely pink, opening in the evening. Stamens 8, in two circles. Stigma long, 4-part; ovary 4-nested. The fruit is an elongated pod-shaped box, opening through 4 valves. Seeds small, numerous, without kite.

Table for determination of the species

1    Annual basal rosette adjacent to the soil. The leaves are dull. The top of the inflorescence straight. The tips of the sepals in the bud fit together. Corolla longer than stamens ....................................................................................................................... 1. — O. biennis L.
1* Annual basal rosette raised above the soil at 5 - 10 cm, leaves pointed. The top of the inflorescence during flowering bent. The tips of the sepals in the buds below the tip diverge. Corolla equal to the stamens ........................................................................ 2. - O. parviflora L.

From:   „Флора на Н. Р. България”, том VII, БАН, София, (1079)

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"Sundrop" redirects here. For the soft drink, see Sun Drop. For the fruit tree, see Eugenia victoriana.
"Evening Primrose" redirects here. For the musical, see Evening Primrose (musical).
"Suncup" redirects here. For the snow surface texture, see Suncup (snow).

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Oenothera is a genus of about 145[3] species of herbaceous flowering plants native to the Americas.[4] It is the type genus of the family Onagraceae. Common names include evening primrose, suncups, and sundrops. They are not closely related to the true primroses (genus Primula).


The species vary in size from small alpine plants 10 centimeters tall, such as O. acaulis from Chile, to vigorous lowland species growing to 3 meters, such as O. stubbei from Mexico. The leaves form a basal rosette at ground level and spiral up to the flowering stems. The blades are dentate or deeply lobed (pinnatifid). The flowers of many species open in the evening, hence the name "evening primrose". They may open in under a minute. Most species have yellow flowers, but some have white, purple, pink, or red. Most native desert species are white. Oenothera caespitosa, a species of western North America, produces white flowers that turn pink with age.[5] One of the most distinctive features of the flower is the stigma, which has four branches in an X shape.[6]


Oenothera flowers are pollinated by insects, such as moths and bees. Like many other members of the Onagraceae, however, the pollen grains are loosely held together by viscin threads, so only insects that are morphologically specialized to gather this pollen can effectively pollinate the flowers. Bees with typical scopa cannot hold it. Also, the flowers open at a time when most bee species are inactive, so the bees which visit Oenothera are generally vespertine temporal specialists: bees that forage in the evening. The seeds ripen from late summer to fall.
Oenothera are used as food plants by the larvae of some Lepidoptera species, including the large white-lined sphinx.[7] The flower moths Schinia felicitata and S. florida both feed exclusively on the genus, and the former is limited to O. deltoides.
In the wild, some species of evening primrose act as primary colonizers, quickly appearing in recently cleared areas. They germinate in disturbed soils, and can be found in habitat types such as dunes, roadsides, railway embankments, and waste areas. They are often casual and are eventually out competed by other species.
Based on observations of evening primroses (Oenothera drummondii), a study discovered that within minutes of sensing the sound waves of nearby bee wings through flower petals, the concentration of the sugar in the plant's nectar was increased by an average of 20 percent. Experiments were also conducted on flowers with the petals removed. No change in nectar production was noted, indicating that it is indeed the flowers that have the job of the ears.[8]


The genus Oenothera may have originated in Mexico and Central America,[9][10] and spread farther north in North America and into South America. With the advent of international travel, species are now found in most temperate regions of the world. In Europe alone there are about 70 introduced species of Oenothera.[4] During the Pleistocene era a succession of ice ages swept down across North America, with intervening warm periods. This occurred four times, and the genus experienced four separate waves of colonization, each hybridizing with the survivors of previous waves.[10][11] This formed the present-day subsection Euoenothera. The group is genetically and morphologically diverse and the species are largely interfertile, so the species boundaries have been disputed amongst taxonomists.[9][12]
From Wikipedia, the free encyclopedia

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Distribution in Bulgaria: (Conspectus of the Bulgarian Vascular Flora) = conspectus&gs_l= Zlc.

References: „Флора на Н. Р. България”, том VII, БАН, София, (1079), Wikipedia, the free encyclopedia


Oenothera parviflora L. - Northern evening primrose, Small-flowered evening-primrose


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