Cowpea is categorized into two types: long cowpea and rice cowpea. Long cowpea is generally eaten as a vegetable, either stir-fried or blanched and served cold. According to Li Shizhen, "This bean can be used as a vegetable, a fruit and a cereal, and it is the best of all beans". Cowpea is a long pod of the genus Cowpea, family Leguminosae, which originated in Africa, with the center of diversity in Nigeria. When cowpea spread to India, the short-pod cowpea species was formed; in Southeast Asia or China, the long-pod cowpea subspecies was formed.
Cowpea, also known as bean horn and banded bean, is native to southeastern Asia and has been cultivated in China since ancient times, especially in the south where it is commonly grown. Young pods can be fried, cold, soaked
or pickled and dried, the seeds can be substituted for food and stuffing, nutritious, tasty, long supply period, as a solution to one of the main vegetables in the summer and fall off-season in August-September. For a long time, due to degradation of varieties inferior, serious diseases, resulting in a decline in yield and quality, is considered to be a low-yield crops, individual areas can not even plant. In recent years, the majority of scientific and technological personnel and vegetable farmers have purified and reinforced the original farm varieties and selected a number of new varieties, which have played a positive role in promoting cowpea production, such as the red-billed swallow of Chengdu in Sichuan Province, the roe skirts of Shaanxi Province, the silver swallow of South China Agricultural University, etc. In particular, since 1980, Cai Junde of the Institute of Horticulture of the Zhejiang Academy of Agricultural Sciences and others have developed a new variety of "Zhi Cowpea 28-2". Especially since 1980, Cai Junde and others from Horticultural Institute of Zhejiang Academy of Agricultural Sciences have developed "Zhi Cowpea 28-2" new variety. It has the characteristics of early maturity, high yield, good quality, high resistance to aphid and mosaic virus disease, wide adaptability, etc. And according to the characteristics of the variety, the research put forward the supporting cultivation technology, which was popularized in 26 provinces and cities in the country, with an average output of 1,969.5 kilograms per acre, an increase in yield of 33.6%, and remarkable economic and social benefits, and it was only three or four years that it was formed as a varietal renewal nationwide, replacing the original excellent variety of red-billed swallow and becoming the main planting variety. In 1987, it won the second prize of national invention, which made cowpea cultivation in China enter a new stage.
Cowpeas are classified into three categories according to the length of their pods, namely, long cowpeas, common cowpeas and rice cowpeas; according to their edible parts, they are divided into pod-eating (soft pods) and pod-eating (hard pods); and the ones that are cultivated as vegetables are divided into long cowpeas and short cowpeas. Cowpea can be categorized into trailing type and dwarf type according to the growth habit of the stem. (1) Sprawling type The main vine and lateral vines grow indefinitely, and the main vine reaches a height of 3~5 meters, with left-handedness, and needs to be set up when cultivated. The leaf axils can produce lateral branches and inflorescences, successive flowering and pods, long growing period, high yield. (2) Dwarf type The main stem is capped with flower buds after 4~8 nodes, the stem is erect, the plant is short, the height of the plant is 40~50cm, and there are more branches. Short growing period, early maturity, short and concentrated harvest, lower yield.