Is this weird projection normal?

Cordyceps for cacti or normal growth?

 

How interesting!

It looks like it is grafted on Dragonfruit (Pitaya) stem. Dragonfruit grows a lot of aerial roots that look like yours (the white part).

Is the growth from the stem or did it manage to worm it's way through the top plant? A photo from a side would be helpful.

 

It looks like its coming from lower down, from the main stem.
I'd cut it back to the stem otherwise it will take over.

 

Thanks for your reply. I bought it at Dobbies so it probably hasn’t come with free dragonfruit!

the white bit has taken about a month to grow to its current size. There aren’t any signs of it elsewhere, as far as I can see.

 

Yeah if it’s not normal I should probably remove that arm!

 

It is what @Selleri suggests, a shoot from the rootstock onto which your plant is grafted, it happens often with any kind of grafted plant.

 

Are you talking about the suspicious fungal-looking white part?

 

The white part is an aerial root, looking for something to attach to, the rootstock is a strong growing climbing cactus, the top part, the round bit, is a different plant which is grafted onto the bottom bit.

You need to cut it off here.

 

That’s fascinating - I had no idea! Makes sense now that I look at it.

Thanks so much @pete and @Selleri for your replies!

 

@Mountain_Goat If you want a free Dragonfruit plant, you can pull the arm off, let it dry for a day or two and then plop it in a small pot. It should root easily and turn into a vicious, vigorous and rather ugly plant

(Or, it could turn out that the root graft part is some other type of cactus... interesting experiment)

I grew my Dragonfruit from supermarket fruit seed: