I am curious to know how long a silica gel dried leaf specimen collection can remain viable for applications requiring high molecular weight (above 10kb) DNA (kept at room temperature) . I've often been told that if the leaf material is still green, you're good to go, but obviously that's not really very scientific. Publications that deal with this seem to be few and far in between, and the words "long term storage" are thrown around regularly, but how long is too long?