[<i>Opuntia</i> Cactus]

North Seymour, Galápagos, July 19, 2011

I'm not really sure which Opuntia this is. It's probably Opuntia echios, which is present on North Seymour and as this one did, grows in association with the Palo Santo (Bursera graveolens, a Gumbo Limbo relative).