A thicket is a very dense stand of trees or tall shrubs, often dominated by only one or a few species, to the exclusion of all others. They may be formed by species that shed large numbers of highly viable seeds that are able to germinate in the shelter of the maternal plants.

What is the briar patch a metaphor for?

"The briar patch," says Wagner, "is a symbol of the commons, the unenclosed, unowned land that provides refuge and resources that sustain the life of the community."

What do you mean by Briar Patch?

(literally) A dense thicket of thorny plants; ground made impassible by the impenetrable overgrowth of prickly vegetation. -I'm sick of going over and through every obstacle on the hill.