[Quiteria]

I found this that seems to answer why they've only started blooming in the past few years:

Organ Pipe Cactus can live to over 150 years in age, and will only produce their first flower near the age of 35. Organ pipe cactus will bloom in May and June, opening its white, creamy flowers only at night. Flowers will close up again by mid-morning, and very rarely remain open into the afternoon. This leaves very little time for daytime pollinators to feast on the sweet flower nectar. Lesser long nosed bats do most of the night pollination, and over the centuries, have developed a unique relationship with these cactus.

quoted from the Organ Pipe National Monument website.
https://www.nps.gov/orpi/learn/natur...ipe-cactus.htm