DISOCACTUS NOPALXOCHIA HORICHII-2022 photo 3

It is a great confusion:

Nopalxochia horichii and Disocactus horichii are two different taxa that have nothing to do with each other other other than the eponymous name.

Disocactus horichii Kimnach, Cact. Succ. J. (Los Angeles) 51: 169 (-170), fig. 2 (1979).
Nopalxochia horichii Kimnach, Cact. Succ. J. (Los Angeles) 56: 6, figs (1984).

What has become of these two taxa today?
Disocactus horichii has become a synonym of Pseudorhipsalis acuminata

Nopalxochia horichii has been made a synonym of Disocactus kimnachii by Rowley and is probably a hybrid, so not included in my book.

Driven by curiosity, I managed to read Myron Kimnach's article in the Cactus and Succulent Journal (USA 1984) which goes into great detail about

let think on the contrary, that the plant is neither a natural nor a horticultural hybrid.

In doubt, Myron Kimnach decided to publish the species as Nopalxochia horichii Kimnach sp. nov. in the hope that later botanists would remove the doubt.

I put at the bottom of this page an excerpt from the article by Myron Kimnach that I mentioned above. In this excerpt, the author argues about his doubts about whether the plant is a botanical species or a natural or horticultural hybrid.

At the beginning of 1971 Clarence K. Horich was visiting the village of San Isidro de Coronado, some 9 km northeast of San José, Costa Rica. He had not come to engage in his usual activity of collecting new or rare plants but to visit a former neighbor. Despite the trip’s purpose, he was about to discover the showies-flowered cactus yet known from Costa Rica.
Along the trails west of Rio Durazno, at the lower level of the cloud forest northeast of San Isidro, he encountered a tree inhabited by a profusion of epiphytes : orchids, ferns, bromeliads and peperomias, as well as the pendent stems of what appeared to be an epiphyllum. Noting that these stems were unusually thick, he took several cuttings of these to the Huntington. Two years later the Huntington plants produced flowers, which were unexpectedly large and red. Similar to those of Nopalxochia, they were certainly the largest colored flowers to be found among Costa Rican cacti.
There were some puzzling things about this discovery. If it were truly a native species, how could such a conspicuous flower have gone unnoticed so long and in a place so close to the capitol city ? It seemed likely that it was a hybrid that had escaped from cultivation or that our plants were the result of mixed labels, and I therefore asked Mr. Horich to return to the site and look for more plants.
Although Costa Rica has already set aside 25% of its land as preserves, most of its magnificent forests are rapidly being destroyed because of development. When Horich returned to the original site five years after his previous visit, numerous new houses had been built in the area and many of the trees along the trail had been cleared or cut down and left lying. All that was left of the original tree was a heap of dead branches, but from among the epiphytes still trying to grow in the detritus he retrieved stems of Epiphyllum thomasianum and another that resembled that of the red-flowered species and so it proved to be upon flowering at the Huntington in 1982. Horich (1983) has given an account of these two visits to San Isidro.
It had now been verified that this entity grew in the wild state, yet I was still skeptical that it was a natural species. For one thing, it looked like a hybrid--perhaps between a heliocereus or a nopalxochia and Epiphyllum crenatum (most probably the long-cultivated clone commonly called E. X cooperi) ; such a parentage could explain the often trigonous stems, the rather pale rosy color of the flower, and the diffusely arranged outer tepals.Also, it was much more easily grown than other species of Nopalxochia, perhaps because of hybrid vigor.
On the other hand, several factors argued against hybridity : first, none of the possible parents (E. crenatum, Heliocereus or Nopalxochia) were known to grow wild in Costa Rica, so that it was not likely to be a natural hybrid ; second, according to Horich, there had been no « orchid cactus » hybrids cultivated in Costa Rica until he brought several from Germany some years after his discovery of the new plant, so that it was just as unlikely to be an introduced hybrid ; finally, the two-angled stems were thicker than those of any known epiphytic cactus species or hybrid, with age becoming nearly oval in cross-section.
Although one may conjecture about the origin of this new discovery, it seems best to publish it now as a species and leave its ultimate analysis to future botanists. It also seems best placed in Nopalxochia, though the receptacle is unusually long, and the pericarpel bracteoles abnormally small, for that genus. The predominance of flat stems and hairy rather than spiny flowers would support its inclusion in Nopalxochia, rather than in Heliocereus.
As with Disocactus horichii (Kimnach, 1979),this species is named after its discoverer, Clarence K. Horich. Resident in Costa Rica since 1957, he has a profound knowledge of the flora of that country and was most helpful as a guide and companion during my visit there in March of 1983.