I've found GRIN and PLANTS to be useful databases (those links both go to H. glabra). Both databases provide links to other databases, and in the case of GRIN, references to dead-tree publications.
By starting there and following links, I end up at efloras (another useful database that links out to yet more). Here, I see:
Roadsides, dry or rocky, sandy places; 0-1200 m
Both efloras and PLANTS have maps showing the US distribution, and both mention worldwide distribution. One link to a European database yields a page that says:
Distribution: Al Au Be Br Bu Co Cz Da Ge Gr He Ho Hs Hu It Ju Lu Po Rm Rs(B,C,W,K,E) ?Sa Si Su Tu [Fe No Rs(N)]
Most of Europe except the extreme north
Based on this information, you can at least make a guess about the climate and soil. Some of the primary sources cited in these databases may give you some of the community information you are looking for. You will probably need to go to a university library to find some of those publications.
Beware that garden plants may be so completely bred and domesticated that finding a "native community" doesn't make sense. You might instead have to look at wild ancestors of a given plant.
I just added a note to this question about scientific research on companion planting and it occurs to me that it may be relevant here as well. You may be able to glean information about native plant communities by researching permaculture "guilds", which are groups of plants assembled by permaculture practitioners that work well together. Guilds aren't necessarily copied from natural plant communities, but they are often inspired by plants that work well together in nature. This would be an alternate starting point on your paper chase, providing a different viewpoint on how things fit together.