Both photos are oversaturated, the shadows are underexposed, and the sky has a lot of color noise. The second photo has a depth of field that is too shallow.
There's not doubt these probably will make for excellent prints, but when viewing between 100%-200% there are noticeable technical flaws.
The Jolon Sunset Trees photo had noticeable artefacts in the sky and halos around some of the leaves at the top.
The wildflower photo has noticeable noise in the mountains.
I agree with @Ralph Lear, both are underexposed in the shadows. I'm sure this was on purpose for artistic reasons, but it works better for stock to have a more even exposure.
Good luck with future submissions 🙂
As both @Ralph Lear and @George_F commented the photos are overprocessed with the colours saturated to the point of not looking natural. Unfortunately artistic liberties aren't what stock customers are looking to buy. They want neutral, natural looking photos to which they can apply their own artistic flair to suit their projects. Like George mentioned, take a look at your photos at least at 100% magnification.
A lot of issues become very clear. The noise, halos, lost details to the point where these images look less like photographs and more like artistic paintings. Both look like great scenes, unfortunately because of the over post processing they don't fit in with the stock photography needs.
Here are some resources that you might find helpful:
This is one of the cases where "less is more" - less artistic editing is more desirable. I'm sure you'll do great with your future submissions and wish you success.
Well I am very surprised. Thank you for your kind and perceptive comments. I understand all of these comments. There is no need to argue the merits one way or the other.
I am in the process of uploading 40 years worth of photography. This means scanning a variety of cameras, lenses and additional photographic equipment. View camera, Nikons, Infrared, time lapse, and drones
I also understand the needs of the stock industry. But this is much like the music industry. You can produce popular music or you can produce original music that will stand the test of time. Some of the greatest artists best performances are not the most popular. I can show you the best of Bruce Springsteen and the best of Dylan. Not their most "popular" songs or selections.
I do have a problem with the procedure of pixel peeping. And to be honest, despite the above, 80% of all my submissions have been accepted. It's about 15 to 20% that are rejected. I think some of the rejections are traceable to the D 600, which was an exceptionally "dirty" camera.
So again thank all of you for your kind comments. One last comment. I think I also suffer from a new monitor. It's a 32" 4K LG monitor that is probably much brighter than what you are seeing. So there may be an issue of calibration that produces the differences in what I see and what the community sees.
I am also a moderator of two of the most successful Flickr groups (Apollo and Dionysus and I Need a Tree) for over 6 years. I select nothing but the best artistic photography. An advantage and disadvantage. Because I know what is good art. That may not be good stock photography.
Attached is single example of a accepted image (my wife in the distance)
You said you're scanning a lot of photos. Were these scans by any chance?
No these were not scanned. In fact, most of the scanned images have been accepted. I may re work and re submit.