In August 2017, I visited the Atlanta Botanical Garden. It was beautiful and I took many photos. As always the plants that stayed with me were the ones I had not seen before. I remember vines with beautiful pea-like flowers, about 2 inches wide, wrapped around dead trees, which were painted (“art”). The flowers were blue/purple with a yellow inner strip and the green leaves reminded me of Kentucky coffee trees. Obviously it was a tropical vine in the legume family (Fabaceae) but I could not find a sign. Later when I got home, I stumbled across the same plant on Facebook only with cobalt blue flowers. Its name, I learned, was butterfly pea (Clitoria ternatea).
The Facebook post said the flowers were used for an herbal tea. I had no idea this pretty vine had herbal qualities. I researched online and discovered that the cobalt blue variety is well-known in Asian countries. The flowers are dried and sold in bags but one can purchase a powdered form or an extract. The flowers can be brewed alone or combined with other herbs such as lemongrass, ginger, and mint. The blue comes from anthocyanins, which are antioxidant compounds, similar to blueberries.
When brewed with water the tea is cobalt blue. 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. Apparently 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. The cobalt 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 would be grown as an annual. The vine grows rapidly in the summer and needs support so an arbor is ideal but would be interesting to try it in a hanging basket. As a member of the pea family, the plant fixates nitrogen and is good for the soil. The vine can take full sun to light shade and is drought tolerant. There are several varieties, some have cobalt blue, lavender, or white flowers in single or double flowered forms.
This is not an easy plant to find here in Virginia but it seems that once you have the plant, you can let some flowers go to seed and collect the pods for next year. Last week I was in Florida and toured a friend’s garden. He was growing this plant in a large container with a trellis. I was so excited to see the butterfly pea again and explained how I was interested in growing it. He had a plastic bag full of the seed pods and offered me some. I took a handful of pods which by now had dried and split open and brought them home. This week, I plan to sow the seeds outside and grow butterfly pea plants in order to experiment with novelty drinks!