Where is the seedling vascular bundle?

[eamnav215]

Hello friends.
Today I made 3 different grafts: 2 Astrophytum Asterias (2-3 months) and 1 Echinofossulocactus zacatecasensis (3-4 months) on Hylocereus rootstock each.
But when I made the cuts, I noticed that the seedlings had 2 vascular bundles.


This made me feel puzzled, because I wasn't very sure about how to fit the vascular bundles of the root stock and the scion. Time ago a friend of mine (who has an impresive colection btw) told me that when the scion is a young seedling, the graft would succed as long as the scion is overlaping the vascular bundle of the rootstock, because its tissues are adaptable enough and a junction will form. I'm very curious about it and would like to know a little more about it, just to be a little relieved about the graft that I've done.


A picture of the graft. As you can see, the scion covers all the vascular bundle of the rootstock.


A picture for scale.


A picture of the vascular bundle of the hylocereus rootstock

Any answer will be helpful!

[Hanazono]

I can see vascular bundles which have not developed as a ring yet.
I can see quite often similar ones when I cut very young asterias seedlings.

When you graft very young seedlings, the success rate is increased naturally without an accurate alignment.
Incomplete development of vascular bundle ring on the scion makes this result.

If I grafted the scion and stock on photos, I will align as follow.