I can't guess what species that person was actually referring to, but the claim is not grandiose at all.

Digitalis grandiflora and D. lutea are "truly perennial", and are very carefree, attractive and long-lived plants... if lacking a bit of the cachet of the bigger purple jobs, where the flowers completely encircle the stems. D. grandiflora is my favorite, and I let them seed freely throughout the yard (well, heck, I guess I do that with pretty well everything, LOL!)

Penstemons are a great group - very interesting - loads of species. I've found many species that do very well here, both in the crappy clay soil, and in "improved" garden conditions (and in troughs, as well). I'd imagine they'd be less happy in wetter, more humid areas, but the dryness here seems to be very much to their liking.

I bought 3 last year calles Digitalis Mertonensis that was advertised as a true perennial. They did not come back this year, however just the other day I noticed little "seedlings" coming up a couple of feet away from where they were planted last year. Now whether they are seedlings from them or another variety I tried a couple of years ago remains to be seen. They are only about 2 inches tall right now, so whether they even survive the winter is another story!
Linda

Completely agree with ABgardeneer. Digitalis grandiflora and D. lutea are wonderful perennials and good reseeders. This year, quite by accident, I put Geranium 'Rozanne' in the vicinity of D. grandiflora. A wonderful combination with the bright blue flowers of the geranium poking up midst the soft yellows of the Digitalis. Looked like I had planned it!
Jan