Can Coffee Trees Really Produce Pink Flowers?

Coffee trees normally bloom with white, five or six petaled flowers in clusters along thin branches, and the denser the bloom, the more cherries farmers can expect at harvest. In rare cases, coffee trees can produce pink flowers instead, and the cause comes down to two distinct sources: natural genetic variation and spontaneous chromosomal mutation.

According to Oliveiro Guerreiro Filho, a genetics and plant breeding expert at Brazil's Campinas Agricultural Institute, one pink-flowering type is the naturally low-caffeine variety Racemosa and its hybrid offspring Aramosa. The other is Purpurascens, a spontaneous chromosomal mutant. Unlike most arabica beans, the Guatemalan estate El Socorro commercialized that mutant trait and went on to win Cup of Excellence awards with it.

Coffee trees blooming with clusters of white flowers usually signal that the harvest season is approaching; the denser the petals, the more fruit can be harvested. The coffee flowers we are familiar with are mostly pure white, made up of five or six petals arranged in strings along thin branches. Every year in February and March, the coffee trees beside Front Street Coffee's shop bloom at random times, releasing a fragrance similar to white-flower varieties such as jasmine, magnolia, and thyme. But did you know that in extremely rare cases, coffee trees can actually produce pink flowers? This article will introduce the two causes behind pink coffee flowers—the natural variety Racemosa and its hybrid offspring Aramosa, as well as the spontaneous chromosomal mutant Purpurascens—and tell the story of how Guatemala's El Socorro estate commercialized this mutant trait and won Cup of Excellence awards.

For millions of coffee growers around the world, once white and fragrant flower clusters appear on coffee trees, it means the harvest season is about to arrive. The more vigorously and densely the flowers bloom, the more coffee cherries the farmers can harvest.

In our conventional understanding, coffee flowers are mostly plain and elegant pure white, composed of 5 to 6 petals, with inflorescences hanging in strings along thin branches. Every year between February and March, the coffee trees beside Front Street Coffee's shop bloom at irregular times, giving off a fragrance similar to white-flower varieties such as jasmine, magnolia, and thyme, which is refreshing and delightful.

However, you may not know that in some extremely rare cases, coffee trees can also bloom with pink flowers. What exactly causes this difference?

In an interview report by Perfect Daily Grind, Oliveiro Guerreiro Filho, a genetics and plant breeding expert at the Campinas Agricultural Institute in Brazil, pointed out that coffee trees capable of producing this rare pink flower mainly fall into two variety types.

One type originates from natural genetic variation in coffee plants. Research has found that some specific varieties have a higher probability of producing pink flowers, such as the naturally low-caffeine variety Racemosa (Coffea racemosa) and its hybrid offspring Aramosa.

Racemosa (also called racemose coffee) is native to southern Africa. It is a coffee with naturally extremely low caffeine content and is also one of the oldest varieties, first introduced to Brazil in 1954. Afterward, agricultural researchers in Campinas crossed it with Arabica and, through trait selection, obtained the Aramosa variety, which is currently grown only on some small estates in Brazil.

Typically, Arabica beans have a caffeine content of about 1.2%-1.6%, while Aramosa coffee has only 0.7%. However, the low-caffeine trait also reduces the variety's resistance to pests, so it needs to be planted at higher altitudes. When the flowering season arrives, Aramosa coffee trees produce rose-pink flowers, and the ripe fruit is purplish-red.

Another type of coffee tree that can produce pink flower clusters is called Purpurascens (purple leaf), caused by spontaneous mutations in the plant's chromosomal DNA sequence. Gene expression determines the color of the entire plant. The young leaves, new stems, and stipules of Purpurascens coffee trees are all purple, while the flowers are a beautiful pink. Researchers also note that Purpurascens mutant coffee trees usually have lower yields and are more susceptible to pests.

For example, in 2009, the owner of Guatemala's El Socorro estate discovered the purple-leaf and pink-flower traits of Purpurascens coffee among the Maracaturra seedlings grown on the estate, and then selected them for separate cultivation. After harvesting, they found that this mutant's cup profile was quite outstanding, with fruit acidity reminiscent of blackcurrant and ripe plum, so they commercialized it through grafting techniques and subsequently won awards in several Guatemala Cup of Excellence competitions.

Most coffee growers may never have seen pink flowers on coffee trees and perhaps never will. However, as producers and researchers continue to develop hybrid varieties, perhaps in the near future we will see more coffee plants blooming with pink flowers.

- END - Front Street Coffee

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The above content is compiled by CoffeeHunters, a coffee news website.