I saw this at the Denver Botanic Gardens. That would make it hardy to around Zone 5. It is growing in a rock or alpine bed there. I believe the foliage reached 6". I don't think it was receiving full sun either.
Altagardener, you will make me very happy with those seeds. Please have a look at my have list to see if you can find something interesting for you. If you can't find something, have a look later, I'll be adding seeds every week.
I was at the Denver Botanic Gardens today and I found another Hieracium species you guys might find interesting. The ID stated on the sign is Hieracium tardans, Asteraceae, Switzerland. However, I am not so sure that it is a valid species. It is listed on ZipcodeZoo but isn't recognized by USDA's GRIN.
I took a couple of photos which are not good at all but I think you will get a general idea of how they look. The leaves form an attractive mat.
GRIN is not a complete botanical listing, nor does it claim to be. It is mainly agricultural plants, so I would never expect Hieracium to be included.
Gathering seed from botanical gardens is most likely forbidden without special permission. That said, some places might simply say "go ahead". Others may want you to give them a list of everything you harvest. It just depends on the individual gardens. The DBG does harvest a lot of seed from their rock gardens, and distributes them via several rock garden societies and other botanical gardens, etc. throughout the world.
I always assumed (correct me if I am wrong) that the USDA data base was only for what grows in the US natively or as an alien, since mapping is only for the US.
Frankly, I don't think any one site can be completely complete. Names are constantly changing, and there are always debates as to the validity of certain latin names and whether they warrant species/subspecies/variety/etc. status. I guess my favorite is zipcode zoo for that, since it is quite user friendly, and includes many footnotes in the chronology of naming the particular plant.
For identification, boy, I use many sources, and sometimes I still get no answers. I might look and see if it is listed or can be keyed in the eflora.org sites. I have many bookmarks for genus sites (although once again none are all encompassing), like penstemon, crocus, fritillaria, Lilium, saxifraga, sedums, etc. Maybe we should start a new thread regarding this, and probably best on the ID forum?