Blue.

。Several plants that can extract blue dye indigo are collectively called. There are already accounts of blue in ancient Chinese Book of Poems and Rituals. Plants for indigo vary from place to place. Ming Dynasty Song should star in the book "Tiangong Kai" records that tea blue (i.e., blue), indigo, horse blue, etc. can be made of indigo. The main indigo plants cultivated in China are:

blue is a two-year herb of the crusader. It has always been commonly known as Daqing. The plants are smooth and hairless. A leaf-based semi-hold stem or circle. Short-angle fruit moment round, the top round blunt. Originally from China, it is cultivated in Jiangsu, Henan, Guangdong, Fujian and other provinces. Another European azure is native to Europe. Both are made of leafy indigo. In Chinese medicine, the blue leaves are called big green leaves, and the roots are plate blue roots, which are hot, cold blood and antidote.

is an upright shrub of the bean-blue genus. Also known as blue. The branches have silver-white T-hair. Feathery re-leaf with hair on both sides. Cylindrical, 2.5 cm long, hairy. There are 5 to 10 seeds per pod. It is of tropical origin. China has cultivated or escaped into the wild. Indigo with leaves. The drug has a cold blood, detoxification effect.

blue is a year-old herb. The stems are purple-red and the leaves darken and blue when they dry. Spiked flower sequence, flower red. Thin fruit is three-angled. It is distributed all over China. Leaves for indigo and medicinal use.

is a perennal herb of the Coma blue genus. Produced in southwest and south-central China. The leaves can be made indigo and can be drugged with roots and root stems.

indigo as a direct dye, but do not use dyeing media to dye animal and plant fibers. Chinese indigo as early as the Sui and Tang eras have been exported to West Asia, spread to Europe, and spread to Japan. Before the chemical synthesis of indigo, Chinese indigo products were well-known on the international market. Indigo can also be used as an food coloring.

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