The plant returns to my garden every year, with branches that are meters long. Densely covered with very sharp thorns, even on the underside of the leaves. I have never seen the plant anywhere else, is it native?
Answer
Dear Josh,
This is a Blackberry (Rubus spec.), the exact species is very difficult to determine as many species easily interbreed in the wild. Many species are native, you can find them mainly as undergrowth in forests or in hedgerows…
ps blackberries and roses have spines, not thorns….

Answered by
drs. Marc Reynders
Biology, systematics and evolution of seed plants. Specialized in tropical Cyperaceae.
http://www.ugent.be
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