Some Tillandsia species easily form hybrids with other Tillandsia species and some like Tillandsia complanata Bentham (1846) even hybridize with species of other genera. Tillandsia argentina Wright (1907) is one that easily forms hybrids with other species. So probably there is a lack of physiological barriers between this and other species that probably did not occur in the past in the same distributional area. It is known that unrelated Tillandsia species that do not grow in the same area can easily be crossed with each other, because there are no physiological or biotic or abiotic barriers which are needed to avoid hybridizing. As biotic factors you can think of pollinators that do not visit both species or different flowering time during the year, and as an abiotic factor different elevation.

Species from other genera are less compatible, so those hybrids occur less often, but in the case of Tillandsia complanata it is known that it does hybridize with Guzmania monostachia (L.) Rusby ex Mez (1896) and has been described as Guzmania barbiei Rauh (1985). Derek Butcher noted that Harry Luther already suggested in September 2004 that this is a natural hybrid between those species and that Joachim Saul reported never having been able find the species of it in the vicinity of the type locality.

Now what about Tillandsia argentina? Rauh and Weber both described several Tillandsia species that turned out to be hybrids and were very rare because, to my knowledge, they were not found again and thus known only from the type locality. Tillandsia argentina forms hybrids with T. tenuifolia Linnaeus (1753), T. aeranthos (Loisel.) Smith (1943), T. didisticha (E.Morren) Baker (1888), T. mubriae (1986) [as Tillandsia x 'Tanti" in the BCR, not described yet] and 77 albertiana Vervoorst (1969).

Over the years I collected information about those taxa and tested the pollen germination on an agar plate (bad germination is an indication of hybrids) and studied the pollen uniformity (normally pollen of a species are uniform but varies in size in hybrids). Specimens were photographed and documented and flowers were dissected and compared with that of putative parents.

Taxonomy

x Guzlandsia barbiei (Rauh) Gouda comb. nov.

Guzmania barbiei Rauh...