River primrose again
The tallest of all our evening primrose species in central Texas is Oenothera jamesii, known as river primrose. I’d discovered a good colony of it in the bed of the North Fork of the San Gabriel River near Tejas Camp in Williamson County in mid-September of 2021, so on September 12th this year I went back there and wasn’t disappointed, as you see above. And here’s a much closer look at one of the low flowers:
© 2022 Steven Schwartzman
Portraits of Wildflowers 
The close-up shows the messy pollen strands I’ve noticed in other Oenothera species. I finally explored a bit, and found plenty of mentions of those pollen strands. It seems the flowers are pollinated by bees and moths that have a specialized ability to cope with their stickiness, and the strands themselves have been well studied:
“An interesting attribute of the Onagraceae is their distinctive pollen characteristics… [which] are relatively large, and are more or less triangular due to three protruding, stopper-like apertures. Pollen grains are connected with viscin threads, which are composed of an elastic and somewhat viscid material. Viscin threads may vary in number and structure. These slender strands also occur on pollen of certain Ericaceae.”
Not only that, the flowers are pretty!
shoreacres
September 21, 2022 at 6:51 AM
Someone our age who grew up in Texas told me that kids used to rub evening primrose flowers on each other’s noses to turn them yellow. The pollen strands may be messy, but kids don’t mind messes (they may even crave them).
I’m glad you did some research; I never knew that “the flowers are pollinated by bees and moths that have a specialized ability to cope with their stickiness.”
And yes, the flowers are pretty (as well as pretty large).
Steve Schwartzman
September 21, 2022 at 7:28 AM
I don’t think we have this particular species of evening primrose, but I like all variants, be they white, yellow, or pink (are there any others?).
tanjabrittonwriter
September 21, 2022 at 10:47 AM
You’re correct that this tall species doesn’t reach Colorado. The USDA map shows it only in Texas, Oklahoma, and Kansas.
I’m with you in liking all the evening primroses I’ve seen. Most here have yellow flowers, the one big exception being the pink evening primrose. Sometimes the pink is so pale it seems white.
Steve Schwartzman
September 21, 2022 at 1:18 PM
Our evening primroses are just past peak now but there are still bits of yellow here and there. They are not as crinkled as your river species.
Steve Gingold
September 21, 2022 at 4:29 PM
The peak bloom of our other evening primrose species is in the spring. Which species of evening primrose do you have there?
Steve Schwartzman
September 21, 2022 at 9:38 PM
Evening primrose flowers are delightful. 🙂
Ann Mackay
September 24, 2022 at 12:46 PM
As you’ve seen, we fortunately have a bunch of native evening primrose species here.
Steve Schwartzman
September 24, 2022 at 1:53 PM