The Cattleya orchid plant I purchased a number of years ago came with a small plant that that strings along with semi-circle leaves. This small plant kept on growing without any problems. But today, to my surprise, I noticed that all along the strings of the plant there are some gray circular matters on them. Please let me know what this plant is call, what the gray matters are, and if it is harmful, what I should do about it.
Although your photo is very tiny, it looks like the little straggler might be Ceropegia woodii (also called Chain of Hearts, Collar of Hearts, String of Hearts, Rosary Vine, Hearts-on-a-String, Sweetheart Vine). It is a tropical/subtropical trailing plant that often sits on the surface of potting soil, and has purple thread-like stems and green, heart-shaped leaves that have silver markings on the top side.
As for the “circular matter” that seems to have appeared – these are likely little tubers that emerge from the nodes or bases of the leaves, along the stems. You can plant the tubers to form new plants. The best way to do so is to leave the tuber attached to the mother vine, and simply press the tuber gently into soil in a nearby pot. The tuber should be half-covered with soil, so it will be sticking out of the soil a bit. Once it is rooted (this may take weeks or months), cut the connection between the new plant and the mother. However, it is easier (but may not work as well) to just detach the tuber from the vine (it is fine to leave bits of vine attached) and plant the tuber.
The Ceropegia and its tubers are not harmful to the orchid – this is just another plant, ready to multiply!
For more information see
Drought Smart Plants. How to grow Ceropegia woodii
University of Wisconsin-Extension Master Gardener Program. String of Hearts, Ceropegia woodii
A Diane Mumm Garden YouTube Video, “Unique Ceropegia Rosary Vine- A K A String of Hearts”
Finally, if your “circular matter” does not sound like they might be the tubers discussed above, please send additional photos that are close-ups, so we can more clearly see what these might be.