I wish I could say I was posting a photo of the Argentina landscape I took myself, but these were emailed to me last year. Friends had sent me these photos as well as the ones of Jacaranda mimosifolia that I posted last year.
I never got around to posting these cacti photos. They'd be in bloom again now, so they merit some attention. The plant at the bottom left is most likely Lobivia longispina. I write "most likely" because there's a fair amount of dialogue on the differences between Lobivia and Echinopsis, or whether the two genera are one and the same.
But based on the long spines, I'm hedging this is Lobivia longispina. Both genera thrive in the dry soil comprised of degraded volcanic substrates. They also most often occur naturally within a limited elevation (1800-4000 m) and on north, east and northeast faces (read: they don't like direct sun).
Apparently the pulp of these plants is quite tasty though I hope I'll never be thirsty enough to wrangle with one of these plants when on a Patagonian hike.