Lu Cao

Lu Cao is the whole herb of Humulus scandens (Cannabaceae), Asian or Japanese hop, an annual or short-lived perennial climber widespread across East Asia in thickets, hedgerows and waste ground. Stems can reach 3–5 m, are angular and densely armed with retrorse hooked prickles that cling readily to surrounding vegetation and to skin. Leaves are opposite, long-petioled, and palmately five- to seven-lobed with sharply serrate margins; both surfaces are rough with stiff hairs. The species is dioecious: male flowers are small, greenish, in loose terminal panicles, while female flowers form pale green, cone-like pendulous catkins with overlapping ovate bracts that enlarge in fruit. The plant has a distinctive bitter herbaceous odour when bruised.