Seedling rib count

[Wood Chuck]

T. Scopulicola seedlings have 7 ribs and were OP, seeds from T. Scopulicola plants, that were the only plant flowering, have no more than 6 ribs, most of them have 5 ribs. I have T. Pachanoi Pc, but they did not flower until the flower on T.Scopulicola were dead and shriveled. Maybe I got it wrong and there was a T. Pachanoi PC flowering..

[saguaro]

Are you confused that the seedlings have more ribs than the parent plants?

 

I don't think rib count is phylogenetically informative in this case.

[Ishmael Fleishman]

I got 50 Trichocereus pachanoi seedlings from a 6 rib parent - the seedlings have ribs ranging from 5, to 9 and one even has 10 ribs.

 

Most are 5 or 6 ribs and some have gained and others have lost ribs and they are only 16 months old.

 

Unfortunately no 4 ribs in this batch.

Edited May 5, 2024 by Ishmael Fleishman

[fyzygy]

It's common for young seedlings to have a larger number of ribs to begin with, before assuming their mature form. OP will probably be able to confirm that with the T. scopulicola (which virtually never has more than six ribs, according to Keeper Trout's book on San Pedro). I had one branch of a mature scop with seven ribs, but it eventually reverted to its more common 5-ribbed form. Of course, OP might have an exceptional bunch of mutant freaks. But scopulicola is generally (almost always) 4-6 ribs. 

 

A seedling with 10 ribs could crest, or (more likely) drop a few ribs. I haven't seen a "four winds" pachanoi, a form which is more common among scopulicola and bridgesii. Some specimens do seem to have a propensity for it, but there are no exclusively 4-ribbed trichocereus varieties that I'm aware of. A 4-ribbed branch will often revert to one with 5 or more ribs, in any case.

 

I had a seedling which looked, for a long time, as though it had just 3 ribs! But on melty specimens like that there's often little point in trying to count. Ditto, the crests. 

[Fathom]

As seedlings or even small cuttings grow they transition through phases of maturation that are largely defined by their genes. 

Nearly all forms of San Pedro have more ribs when young than they do when mature. 

Likewise differences in other traits, like spine number, size and arrangement can vary depending not only upon the environmental conditions but also according to the maturity of the specimen in question. 

 

This aspect of San Pedro growth complicates identification efforts and a small cutting or seedlings is unlikely to resemble it's more mature form.