Umm Qays bint Mihsan (may Allah be pleased with her) said: I asked the Prophet (peace and blessings be upon him) about menstrual blood that gets on a garment, and he (peace and blessings be upon him) said: "Scrape it off with a rib-bone, and wash it with water and lote-tree leaves (sidr)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4110