Persicaria tinctoria. Polygonum tinctorium 蓼 大 青 叶 Liǎo dà qīng yè  Indigo   
PART USED: Leaf- Planted in winter and collected twice or three times in summer and autumn
Nature- cold  FLAVOR: Bitter
FUNCTIONS
1. Clear heat, counteract toxic effects, cool blood.[1]
INDICATIONS
1. Fever in a warm disease, macuta, common cold, pneumonia, sore throat, mumps, epidemic cerebrospinal meningitis, encephalitis B, erysipelas, carbuncle.[1]
PREPARATIONS: Dry leaf 9-15 g.[1] Dried, big and complete leaf, dark grey green in color, without impurity such as branch, stem.

References
Inner Path can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Cultivation, Harvesting and Supply.
Brunswick West, Victoria, Australia- 50 seed pack (approx). localseeds.com.au