Bigfruit Evening Primrose, Missouri Evening Primrose. Missouri Primrose, Fluttermill, Ozark Sundrop

Oenothera macrocarpa

(Oenothera macrocarpa subsp. macrocarpa)

ee-no-THEE-ruh ma-kro-KAR-pa

ROYAL HORTICULTURAL SOCIETY AWARD OF GARDEN MERIT

Synonyms of Oenothera macrocarpa (1) (Updated on 12-21-23 from Plants of the World Online): Megapterium macrocarpum (Nutt.) R.R.Gates
Synonyms of Oenothera macrocarpa subsp. macrocarpa (9) (Updated on 12-21-23): Megapterium missouriense (Sims) Spach, Megapterium nuttallianum Spach, Oenothera alata Nutt., Oenothera macrocarpa var. missouriensis (Sims) Carrière, Oenothera missouriensis Sims, Oenothera missouriensis f. elongata F.C.Gates, Oenothera missouriensis f. intermedia H.Lév., Oenothera missouriensis var. latifolia A.Gray, Oenothera missouriensis var. typica Munz

Oenothera macrocarpa Nutt. is the accepted scientific name for this species of Oenothera. It was named and described as such by Thomas Nuttall in the Catalogue of New and Interesting Plants Collected in Upper Louisiana in 1813. 

Accepted Infraspecific Names (5) (Updated on 12-21-23): Oenothera macrocarpa subsp. fremontii (S.Watson) W.L.Wagner, Oenothera macrocarpa subsp. incana (A.Gray) W.L.Wagner, *Oenothera macrocarpa subsp. macrocarpa (autonym), Oenothera macrocarpa subsp. mexicana W.L.Wagner, Oenothera macrocarpa subsp. oklahomensis (Norton) W.L.Wagner. *When an infraspecific taxon is named, an autonym (“type-specimen”) is automatically generated whose description is closest to the (original) species. All have their own synonyms. Plants found in Missouri are assigned to Oenothera macrocarpa subsp. macrocarpa.

The genus, Oenothera L., was named and described as such by Carl von Linnaeus in the first volume of the first edition of Species Plantarum in 1753.

As of 12-21-23 when this page was last updated, Plants of the World Online lists 157 species in the Oenothera genus. It is a member of the plant family Onagraceae with 22 genera. Those numbers could change as updates are made on POWO.

The above distribution map is from Plants of the World Online. Areas in green are where the species is native and purple is where it has been introduced. The map on the USDA Plants Database for the United States is the same. Many maps, including an updated map on POWO, don’t include Wyoming where the species is considered rare (from older maps).

The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations. The maps on iNaturalist are continually updated as members post new observations.

THERE ARE SEVERAL LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH A POSITIVE ID.

I found this Oenothera macrocarpa at one of the local greenhouses on May 26 in 2020. The label said Oenothera missouriensis and that it was an Evening Primrose. Oenothera missouriensis is a synonym of the autonym Oenothera macrocarpa subsp. macrocarpa. It goes by several common names such as Bigfruit Evening Primrose, Missouri Evening Primrose. Missouri Primrose, Fluttermill, Ozark Sundrop, and possibly others. The name Bigfruit Evening Primrose was given due to their strange oddly shaped fruit. Flowers open at dusk and close in the morning except on cloudy days. Luckily, I brought this plant home when there were several cloudy days in a row. Unfortunately, the flowers only last one day (or night). I kind of screwed up and only brought home one plant… They are self-incompatible, which I didn’t know at the time. They need pollen from the flowers of another plant for them to produce fruit and viable seeds… Maybe that is something they should put on the labels.

The map on Plants of the World Online indicates it is a native species in nine states in the United States and part of Mexico.

The Missouri Plants website says plants found in Missouri are referable to Oenothera macrocarpa subsp. macrocarpa. The other subspecies have their own geographic range and possibly overlap. Each subspecies has their own feature characteristics that set them apart from the others.

A few days after I brought this plant home, I put it in the flower bed behind the old foundation where my grandparent’s old home was. It did well over the summer but didn’t return in 2021. Well, I was hoping being a perennial they would return…

Oenothera macrocarpa is a herbaceous perennial wildflower that is well known for its large yellow flowers. Although online maps indicate they are found in several states in the midwest, in some they are only found in a few counties (or less). Some states that are “green” have no county data (USDA Plants Database). 

Oenothera macrocarpa make great plants for the wildflower garden and are available as plants and seeds from a few online sources. If you purchase plants, just remember to buy a few. Hmmm… There is a good-sized colony of these growing in the bed of a bank in town…

Information online says they prefer growing in full sun but will tolerate light shade. They need well-drained conditions in average to poor soil. They have deep taproots, so they are drought-tolerant.

The plants have short stems that can be erect to ascending, sometimes sprawling, especially in a colony. Plants usually grow from 6-12” tall. They can have one or more stems emerging from a rosette of leaves and may branch out. Stems are reddish or purplish-tinged and somewhat hairy.

The leaves grow in an alternate fashion along the stems, are up to 6” long x 1” across, are said to be lanceolate (lance-shaped), oblanceolate, to broadly elliptic. They are kind of wavy, have broadly spaced teeth (dentate), have white veins, and have short hairs (pubescent). Lower leaves have long petioles (leaf stalks), while upper leaves are sessile (no petioles). 

The flowers of the Oenothera macrocarpa may begin to open late in the afternoon to early evening and remain open during the night. On cloudy days they may remain open longer but normally they only last for one day.

Flowers are produced from the axils of upper leaves and have a long and weird floral tube (some refer to it as a calyx tube). Actually, the ovaries are enclosed in the part of the “tube” that emerges from the leaf axils, followed by a long tube with the petals (corollas) on top. Of course, writing a description without a photo to point out the parts is a little confusing… Below the petals, on top of the floral tube, is the calyx that surrounds the buds, which eventually droops downward. The flowers can be around 5” across, have 4 bright yellow petals, 8 stamens with linear anthers, a long style, and a 4-lobed stigma. Plants bloom from May through August.

The above photo was taken at 8:37 AM on May 27. It was cloudy and a bit rainy.

Oenothera macrocarpa produces very interesting winged fruit I will not even try to describe. The seed capsule contains 4-sections (4-locular), that split open (longitudinally dehiscent). Each “locule” produces numerous seeds that are grayish brown to dark brown that are so small they can be dispersed by wind.

The above photo was taken at about 7:30 PM on May 29. We had several cloudy days…

HOPEFULLY, I can find some of these locally again at some point. I will remember to buy SEVERAL…

I have enjoyed photographing and learning about the many wildflowers growing on the family farm and in other areas. The farm is in Windsor, Missouri in Pettis County (Henry County is across the street, and Benton and Johnson aren’t far away). I have grown over 500 different plants and identified over 200 species of wildflowers (most have pages listed on the right side of the page). I am not an expert, botanist, or horticulturalist. I just like growing, photographing, and writing about my experience. I rely on several websites for ID and a few horticulturalists I contact if I cannot figure them out. Wildflowers can be somewhat variable from location to location, so sometimes it gets a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.

I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. Some sites may not be up-to-date but they are always a work in progress. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at thebelmontrooster@yahoo.com. I would enjoy hearing from you especially if you notice something is a bit whacky.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX (GENUS/SPECIES)
TROPICOS (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
USDA PLANTS DATABASE
DAVE’S GARDEN
MISSOURI PLANTS
MISSOURI BOTANICAL GARDEN
MISSOURI DEPARTMENT OF CONSERVATION
iNATURALIST
WILDFLOWER SEARCH
ILLINOIS WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
LADY BIRD JOHNSON WILDFLOWER CENTER
FLORA FINDER
GARDENIA
HIGH PLAINS GARDENING
UNIVERSITY OF ARKANSAS
THE PRARIE ECOLOGIST
ROYAL HORTICULTURAL SOCIETY
U.S. WILDFLOWERS

NOTE: The data (figures, maps, accepted names, etc.) may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and thousands of species to keep up with. Accepted scientific names change periodically and can be hard to keep with. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is one of the most reliable and up-to-date plant databases and they make updates regularly. I make updates “at least” once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂