Species
Macrogonus
This name sits at the centre of an argument that is still going on, and this page sets out what is actually settled about it and what is not.
The name
The International Plant Names Index records Trichocereus macrogonus Riccob. as a validly published name, first published in 1909. Cereus macrogonus Salm-Dyck is the type species of Trichocereus — the name the genus itself is anchored to, designated by Britton and Rose in 1920 and followed by every author since. The treatment now in use keeps Trichocereus as a genus of its own rather than folding it into Echinopsis.Reported by one source, and not corroborated anywhere else.
How growers use the name
Growers use the name loosely, for almost any stout, blue, well-armed column.Too little stands behind this for us to confirm it.
What the 2012 revision did
A 2012 revision reads Salm-Dyck's original description of Cereus macrogonus as the plant later named Trichocereus peruvianus, and fixes the identity by designating a neotype.Reported by one source, and not corroborated anywhere else.
Which name is senior
Under recent revisions macrogonus is the older and therefore senior epithet: San Pedro sits beneath it as a variety, and a good deal of what the trade sells as peruvianus is absorbed too.Too little stands behind this for us to confirm it.
The varieties, and when they were published
Trichocereus macrogonus var. pachanoi was published by Albesiano and Kiesling in 2012, and var. peruvianus by Lode in the same year.Reported by one source, and not corroborated anywhere else.
Where we stand on it
This library does not settle which of those readings is right, and it is not going to: the authorities genuinely disagree, growers have carried on using all three names regardless, and a page that quietly picked a winner would be inventing a consensus that does not exist.
What has been found in the wild
Asked for Trichocereus macrogonus by name, the collectors' own field-number lists return 9 distinct collections from 4 collectors — 6 at Bolivian localities and 3 at Peruvian localities.Reported by one source, and not corroborated anywhere else.
What that record is and is not
That is a record of where the species has been found and written down. It is not a statement about any plant in cultivation, and it does not settle what is growing in anybody's pot.
Names in the library filed under this species
These are entries where a source names this species for the plant. An entry is not listed here because its name looks like the epithet — that would be a guess, and a guess is what this library exists not to publish.
Every feature on this page moves with age, sun and water: a thirsty plant in hard light grows longer spines and a heavier bloom than the same clone in the shade. None of it settles an identity on its own, a clone name is not proof of a species, and a photograph is a pointer rather than an answer.