Marshallocereus aragonii

References

1. [1]The Cactus Family — Anderson E.F. · Timber Press; Portland, Oregon · 2001 · ISBN 0-88192-498-9 ↩︎An excellent work, giving botanical descriptions of virtually all the cacti, together with their range (but not their habitats) and sometimes also a photo. it also contains a long chapter detailing the many uses of cacti and another on cultivation..
2. [2]Flora of Costa Rica — Standley P.C. · Field Museum of Natural History; Chicago · 1938 · http://www.archive.org/ ↩︎Rather dated, but an excellent treatment of the area. Available for download from the internet.
3. [3]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.