Is this dichotomy ?

[eddytrain]

Hi,

I never saw this before on cacti.
Is this what is called "dichotomy" ?

On a Mammillaria :




On a Parodia :

[ElieEstephane]

On the mammillaria yes but the parodia i think is cresting

[DaveW]

The first is dichotomous branching, It is a characteristic of that species and the heads may continue to do it as they enlarge. It is common in some Mammillaria's, though it is theoretically possible in all cacti but more unusual. I have a Pseudolobivia where one head has done it.

http://www.cactofili.org/specie.asp?mod ... rwinskiana

http://www.cactus-art.biz/note-book/Dic ... hotomy.htm

Far less common, but you can even get trichotomy where a plant divides into three branches and exceptionally where it divides into even more.

https://www.ebay.com/p/Mammillaria-Park ... 1073235544

Eventually it becomes hard to draw a line between what is normal branching for the species and what is monstrose or polytomy forming many heads.

http://www.cactus-art.biz/note-book/Dic ... lytomy.htm

Too soon to tell with the other since the crowns do sometimes contort before resuming normal growth, but time will tell.

As I recall in 1979 Ritter named a Notocactus cristatoides (= looking like a cristate) on the tendency for the crown to distort in a similar manner as it grew without actually going cristate,

[eddytrain]

Thanx for your answers !
Have you an idea why this happens ?

[DaveW]

See:-

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4047680/

Then you can explain it to me!

[eddytrain]

2 months later...

[TimN]

I had a Mammillaria years ago that had a three armed meristem that eventually split into 5 distinct meristems. I have two L. williamsii that did dichotomous splits. I enjoy watching these develop! DaveW - Thanks for the reference to the plant science article!

[DaveW]

As I said I had a Pseudolobivia do it on one head. Potentially all cacti can probably do it, but most do not except very rarely. However there are some genera like Mammillaria where a few species characteristically branch dichotomously rather than offset. Really it is akin to a tree forking:-

https://davesgarden.com/guides/pf/showimage/37087/

http://www.llifle.com/Encyclopedia/CACT ... _crucigera

http://mammillarias.org/hot-topic.htm

http://mammillaria.forumotion.net/t1102 ... sempervivi

I have seen pictures of dichotomous Stenocactus on the Web. Not sure the Parodia (Notocactus) has yet gone cristate since sometimes the crowns on our plants do go misshapen but eventually grow out normally. Time will tell, so keep an eye on it.

[eddytrain]

2 years later

[Aloinopsis]

Thank you for sharing an update. That's really interesting.

[eddytrain]

And 5 years later...

[jerrytheplater]

Cool. Thanks for coming back and giving the update.