Acaena's a genus of about one hundred species of perennial herbs and subshrubs in the Rosaceae, native mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a few species extending into the Northern Hemisphere, north to Hawaii (A. exigua) and California (A. pinnatifida). The leaves are alternate, long, and pinnate or nearly so, with 7-21 leaflets. The flowers are produced in a tight globose [inflorescence] in diameter, with no petals. The fruit's also a d… (More on Acaena)