I have grown an indoor Black-eyed Susan vine (Rubeckia Hirta), and recently numerous, raised, tiny bumps appeared on some of its leaf surfaces and stems (pictures below). I would very much appreciate help identifying if this is merely some natural phenomenon, or an infection that might spread to my other plants. Thank you!

Hello and Christof

Very hard to tell, but can you scrape them off with your fingernail? Have you got a magnifying glass? If you scrape some off and look at them through a magnifier, you should be able to see if they are insects or just natural growths. (you might be able to get a picture through the magnifier so we could see better, too)

The way they are situated, the only thing I could think of was scale insects, but they don't usually go out onto the upper sides of the leaves like that. Stems and undersides of the leaves are where they like to attach and suck the juices out of your plant. Are there any underneath the leaves?

If that's what they are, a horticultural oil spray is the remedy. Scale insects protect themselves with a little shell so direct contact sprays like soapy water don't work, except on the nymphs. The oil smothers them.

ChristophGielen to ATP.

I have no idea what the bumps are, but maybe someone can lead you in the right direction. Lots of knowledgable people here.

Welcome to All Things Plants, @ChristophGielen !

Although I don't know what the bumps are on the leaves, I believe what you have there is Thunbergia alata (Black-eyed Susan vine), not Rudbeckia hirta -- which is the wildflower "Black-eyed Susan."

I can't tell from your photo, but the little "bumps" actually look to me like they could be tiny insects of some type, possible juvenile aphids?

Welcome to ATP.
Black-eyed Susan vine is the common name for Thunbergia alata, not for Rudbeckia hirta.

It would be good to try for a closeup photo of the spots as dyzzypyxxy suggested.
Just in case they might be insects I think it wouldn't hurt to use an insecticidal soap.

Edit:
Ooops, cross posted.

I wonder if the bumps are intumescences. I can't find a picture of them on Thunbergia to see how they compare with Christoph's image but this is what intumescences look like on Cuphea:

https://negreenhouseupdate.inf...

and here on Cleome:
https://negreenhouseupdate.inf...

If that's what they are and the cause is believed to be reduced UVB radiation, then perhaps the plant is getting insufficient light. It looks from the pictures as though it may be growing indoors?

Thank you so much for the collective reply - I am new to such a forum. All of these considerations are very helpful, particularly the remark on sunlight - it makes sense that this could be an issue indoors, even though the spot I chose is quite sunny. Thank you again!