Often seen in cocktails on social media, butterfly pea plants (Clitoria ternatea) are vines that bloom beautiful pea-like flowers, about 2 inches wide. Typically, flowers are cobalt blue with a yellow inner strip. A member of the legume family (Fabaceae), the green leaves are similar to Kentucky coffee trees.
The flowers are also available in white, lavender, and a pale light blue, single or double flower, but the cobalt blue is well-known in Asian countries. The flowers are dried and sold in bags, or in powdered form, or as an extract. A tea is made with the flowers, which can be brewed alone or with other herbs such as lemongrass, ginger, and mint.
When brewed with boiling water the tea is blue and can be drunk like an herbal tea. However, when an acid is added, such as lemon juice, the tea turns purple. When an alkaline liquid such as roselle tea is added, the tea turns red. Butterfly pea tea acts like a litmus strip, the color of the drink changes with the pH of what it is mixed with. This does not affect the taste but has transformed butterfly tea into a novelty cocktail drink. You will find lots of cocktail drinks made with the flowers on the internet. The blue flowers also are used to dye food such as custards, puddings, rice dishes, and sticky rice.
Butterfly pea is native to Africa. Here in Virginia it is grown as an annual which grows rapidly in the summer up a trellis or obelisk. As a member of the pea family, the plant fixates nitrogen, which is good for the soil. The vine can take full sun to light shade and is drought tolerant. 
I have not seen the plant sold at local garden centers but you can order seeds online. It is relatively easy to grow from seed and once you have a mature plant, you can let some flowers go to seed to save the seed pods. Save the pods and split open when dried to reveal the seeds. Save the seeds to grow next year.
Here are a few online seed companies: Eden Brothers, Baker Creek Heirloom Seeds, Park Seed, Strictly Medicinal Seeds, and Hudson Valley Seed Company. Include the butterfly pea with your 2025 seed order and try growing magical flowers!
This was popular as a tea when my niece got to that age of wanting to do tea parties. Not only is it amusingly colorful, but it is ideal for young ladies who are limited to herbal tea.