I recently posted a quick article on ashwagandha, the potent anxiolytic and adaptogen, which I highly suggest. The only other compound which rivals its potency and effects is Rhodiola Rosea. Unlike ashwagandha which can be slightly sedating, Rhodiola Rosea has potent energetic effects.
These two adaptogens are similar in potency, but are two different sides of the spectrum as far as effects. Although rhodiola rosea can provoke anxiety in high dosages, it can also dramatically increase energy, focus, reduce fatigue and improve mood through altering levels of serotonin, dopamine and norepinephrine in the brain.
If you tend towards anxiety, I suggest you start with a low dosage, as some can find their anxiety provoked, while others may find it helps their anxiety. Every individual is different.