Many years ago, I remember seeing cacti in the high plains of Colorado
(or maybe it was northern New Mexico or the Texas panhandle) that had
big purpley-red flowers -- I think they were double or semidouble
flowers. Some of them that otherwise looked identical had much less
showy yellow flowers. The cactus were upright, many-branched, and had
long thorns. I believe they were a variety of cholla.

On recent visits to that area, I can only find a few yellow-flowered
cacti, execpt for 1 red plant that I saw in a bed in a national park
(and didn't think it would be a good idea to pinch off a piece.) Is
this enough information to identify which species it was?

Thanks,
Bob