The quite possibly wise P van Rijckevorsel was heard saying:
I am the wrong person for this but to me it looks like a Rubus species,
all too common. It sure feels unfriendly when touched in passing.

Colin Wetherbee schreef
I found a few images of plants from the genus Rubus, but none seem to
look like the plant I've found. Specifically, I found Rubus
spectabilis, Rubus mesogaeus, and Rubus deliciosus. Thanks for your
help, though.
Colin

+ + +
Rubus is both rather variable and a taxonomic nightmare.
A picture like this seems a fair match

http://www.arborea.se/rubodor.htm

PvR