Evergreen is actually a tree/plant type and the other names are all trees which belong to this tree type. The other known names so far are Cypress and Juniper. Cypress is what we would have considered to be RV870 and Juniper is something like RV840, although that's all a guess.
http://en.wikipedia.org/wiki/Evergreen
I like this quote from Wikipedia though:
Idiomatic use
Owing to the botanical meaning, the idiomatic term "evergreen" refers to something that perpetually renews itself, or otherwise remains steady and constant (it does not suddenly halt or "die off", as leaves on a deciduous tree). An evergreen market, for example, is one where there is a constant, renewed demand for an item or items, as opposed to a market which is expected to saturate eventually.






Bookmarks