Information authenticated by Royal Botanic Gardens, Kew:
http://www.rbgkew.org.uk/
Calcareous: Containing free calcium carbonate, chalky.
Deciduous: A plant that sheds its leaves at the end of the growing season.
Ex-situ: Measures to conserve a species or habitat that occur outside of the natural range of the species. E.g. in zoos or botanical gardens.
Perennial: Plants that live for at least three seasons; after an initial period they produce flowers once a year.