Could you post a photo of them - a close up? Desert Rose seedlings don't look like grass, they have a bulbous stem with 2 small round leaflets on top. As you know the stem should have a slightly rounded, swollen look to it. I'd suspect that something else was in the mix and has germinated instead. Was it a sterile soil mix?

Dave

here are the seedlings, and here is a picture from the seeds i have sown. the soil was sterile yes.

Wow, sorry but no way are those desert rose seedlings. And they don't even look like desert rose seeds. They aren't even remotely close as desert rose seeds are long and tubular and a gray color. Either they were mislabeled (most likely) or there was some sort of seed in the mix. Only way to find out what they are is to let them grow.

Dave