Like a thorn or thorns; hence, figuratively, troublesome; vexatious; harassing; perplexing.

bristling with perplexities; "the thorny question of states' rights"

Full of thorns or spines; rough with thorns; spiny; as, a thorny wood; a thorny tree; a thorny crown.

having or covered with protective barbs or quills or spines or thorns or setae etc.; "a horse with a short bristly mane"; "bristly shrubs"; "burred fruits"; "setaceous whiskers"