Lime stone
 

I am thinking of making up a list of orchids that like lime stone/calcium.

Could you help me? Any experience, sites, links, literature accepted.

Thanks :help

Paphiopedilum and Phragmipedium are a couple of types that I know of. I give them crushed oyster shells on occasion. I'm sure there are probably quite a few more that someone else will add to. Good luck with your project.

There is some good information at Paphiopedilum & Phragmipedium Intro Page - AnTec Laboratory go to the the paph reading room and find the article on supplementing calcicolous paphs.
That said I top dress all my pots with a mix of granular lime and crushed sea shell. Its main purpose is to buffer the media and keeping it from going too acid. Marble, limestone, seashell, egg shell and lime are all Calcium Carbonate in diffeant forms. Some just disolve easier than others,

There are quite a few Anacamptis, Orchis, and European Cephalanthera that grow in limestone with pockets of organic debris.

Many of the Chinese Cypripediums love limestone.

The macrobulbon section grows on limestone cliffs too. The plants growing on limestone cliffs are ones with heavy rainfall, and would need the higher calcium to inhibit cell decay?