Re: Juvenile pictures of monstera

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Hello friends!

Steve Marak and I discussed the taxonomy of Monstera karstenianum at length some time ago. I am not sure we finally figured it all out, but here is what I found from the literature (if I am very much wrong, I hope maybe Tom or Peter or Joep or someone else can straighten me out):

Schott (who originally described and defined the genus Philodendron) treated all members of what we today call Philodendron subgenus Pteromischum as Monstera. Schott (1856) described described Monstera karstenianum. At some point, it was moved with the other Schott Pteromischum species into Philodendron by Engler.

Grayum (1996) revised subgenus Pteromischum, and states that Schott's types of karstenianum actually are a mix of several species. Grayum goes into great detail on P. karstenianum, and why the specific identity is ambiguous, and why the name is currently rejected. So, the correct name for what was originally being called M. karstenianum is probably P. opacum. According to the IPNI and The Plant List, the proper name is now Philodendron opacum Croat & Grayum, 1992. 

But obviously, Don's plant is absolutely a Monstera and not a Philodendron. So what is it?  There is an old name of Monstera peruvianum still bouncing around, and I agree with Malwi that Don's plant seems similar to what was described as M. pinnatipartita.  So what happened to those names?

Madison in his revision of Monstera (1977) treats both M. pinnatipartita and M. peruvianum as  synonyms of M dilacerata. The distribution is Guatemala to Peru.

He writes:

"The Peruvian material of this species generally has only 4-6 pinnae per side, whereas Central American Monstera dilacerata has 7-12 pinnae; this has been the basis for the separation of M. peruviana. However, material from the two areas agree in all other respects and as the extremes of pinna condition are connected by many intermediates there appears to be little or no basis for maintaining M. peruviana as a separate taxon. The lengths of the peduncle and the spadix are quite variable in Monstera dilacerata, the former ranging from 12-27 cm. However, these characters are quite variable, even within an individual plant, and appear to have no taxonomic significance."

I suspect that what we have here is the same situation as "Pothos" and Epiprenum aureum: the name Monstera karstenianum 'Peru' may be just a horticultural name for M. dilacerata from the Peruvian end of the species spectrum of variability, and not really have any basis in science. If someone knows more; please share.

Regardless, Don: that is a spectacular plant!!

Happy days,

Christopher

On Sun, 1 May 2022 at 17:50, Don Bittel <d*@hotmail.com> wrote: