starwatcher wrote on Nov 28^th, 2010 at 9:31pm:

Sparky says (Mark Stensaas) in Canoe Country Flora; "Rock tripe has a completely undeserved reputation as an edible lichen." Franklin Arctic expedition ate it but they suffered from bowel complaints and nausea.

Yes, I'd also seen at least one refernce to rock tripe being used as a purge.  (Not exactly what I'm looking for to help sustain me in an emergency situation.)  Still, I've seen both rock tripe and reindeer moss being used as a survival food ... after 4 or 5 days, you might be hungry enough to give it a try.

But one wonders where Franklin found rock tripe on an ARTIC expedition?  :)

dd