Burnet: either the great burnet (Sanguisorba officinalis), the garden burnet (Poterium sanguisorba), or the common pimpernel (Anagallis arvensis), used medically, according to the Middle English Dictionary.
Sorell: according to the Middle English Dictionary, sorrel (Rumex acetosa) or wood sorrel (Oxalis acetosella) is a common, sour plant, often used medically.
Dragon's crop: Any part of the Dracaena draco plant besides the root.
OR Dragon's Root: The root of the Dracaena draco plant, or a plant within similar genera.