Deebie said:Is this plant the same as acanthorhipsalis monacantha? Or, are they 2 different plants?
Yes, the same plant. Acanthorhipsalis monacantha is synonim for Lepismium monacanthum.
When a plant is reclassified into another genus the rule requires keeping the same second word in the binomial names.
But at the same time the rule requires the according of the epithet (the second word in the binomial name), with generic name (first word of the binomial name).
monacantha is the feminine form of the word and monacanthum is the masculine form. (rule of Latin language).
Monacantha originated in Greek. "Monos" - one , and "akantha" - spine.
So, monacantha, monachantos = one spin. Description suggested by the epithet "one spine" is more or less accurate.
(I am not sure if the word 'generic', used above, it is correct in English. I used it here, with the meaning of the word who show the genus where the plant is classified.)
This cactus like other cacti and many other plants have many synonims.
Other synonims for Lepismium monacanthum: Rhipsalis monacantha, Pfeiffera monacantha, Acanthorhipsalis incahuasina, Pfeiffera incahuasina, Pfeiffera monacantha
In fact the correct, full name of this plant it is
Lepismium monacanthum ( Griseb. ) Barthlott - Bradleya 5: 99. 1987