Dear Josh Young, Jim Shields, Bulborum Botanicum and respected members of PBS;
In reference to Hippeastrum arboricolum, it had been found by the Argentinean collector Carlos A. Gomez Ruppel- the same man that in 1967 discovered H. papilio in a garden in Santa Catarina state(Brazil)- in forest at El Dorado, province of Misiones, Argentina. The forest was erased and the plant was growing in a fallen tree. Apparently it was originally at 25 meters on the tree.
Now, I don't know whether you can confirm this independently, but it would appear that the plant was never in cultivation, and was described purely from the holotype. This herbarium specimen resembled H. striatum, so therefore was assumed to be a synonym of H. striatum, but no evidence exists that I have ever seen, indicating that H. striatum is epiphytic - but I simply do not know.
Anyway, H. striatum is not a native species from Argentina so, in case of having a synonym, it would be, nor more nor less, than H. petiolatum (known by many as H. striatum var. petiolatum).
H. petiolatum is reported in the provinces of Corrientes and Misiones (departments of Cainguas, Capital and El Dorado ). It was once reported in the province of Tucumán , until it was discovered that the species seen was the red form of H. aglaiae.
Traub described two different species with similar features: H. flammingerum for the species found in Santa Ana, province of Misiones; and H. petiolatum for the species found in the province of Corrientes (Monte Justo, department of Santo Tomé). It is known nowadays as H. striatum var. petiolatum, as it is believed to be a variation of the Brazilian species H. striatum. It is a triploid self sterile species which reproduces only by little bulbils that grow around the mother bulb. As this species grows in tropical places near rivers from north-east Argentina and Brazil (there are some reports in Uruguay , as well) in the rainy season these bulbils are driven by surface water flows and travel to sites remote from the original bulb, which ensures not only the spread but also the distribution of this species.
In any case, nothing more than this has been said about this mysterious species, Hippeastrum arboricolum.
Wishing I could have been of any help and sending my warmest regards from a cold night in Buenos Aires.
Yours sincerely, Mariano Saviello
[mariano_saviello83@yahoo.com.ar]