Learning New Words

After a red-eye flight from Nairobi, I arrive at London Heathrow at 5:44 a.m. with a 12-hour layover and a specific mission. I navigate through elevators and escalators to the District underground line, minding the gap as instructed by a computerized, superfluously British voice at every stop. Finally, I step off at Kew Gardens, excited to meet Dr Aaron Davis, Senior Research Leader for Crops and Global Change at the Royal Botanic Gardens, Kew.

Kew boasts the world’s most diverse collection of living plants, featuring over 8.5 million items across its gardens, glasshouses, galleries, ponds, and archives. Founded in 1840, it spans 330 acres and is a UNESCO World Heritage site. Since 1997, Aaron has worked in the Herbarium, located adjacent to the gardens and open to visitors by appointment only. As the world’s leading authority on wild species of Coffea, he has discovered or rediscovered 20 different wild coffee species and named 15. His work encompasses species classification, molecular studies, conservation, climate change, sustainable development, and pest management.

While there are at least 130 species of Coffea, the coffee industry focuses primarily on two: Coffea arabica and Coffea canephora (commonly known as robusta). The global coffee supply depends on these two species, considered the ‘beverage species’ of Coffea.

I was unaware of most of this in 1994 when I first visited Kenya from Los Angeles with my university group. It was my first trip to Africa, my first encounter with malaria, and my first summer drinking coffee. Eager to try Kenyan coffee at source, I naively thought there was only one kind, a notion supported by ’90s my barista training, when coffee bags were, at best, labelled by origin country. In 2017, when embarking on my PhD, I knew I needed to cultivate a genuine relationship with coffee, to learn a new vocabulary—species, varietals, varieties, cultivars, hybrids. And I knew that talking to Aaron would be just the beginning of this quest.

Inside the herbarium

As I follow Aaron into a library-like room filled with drawers, books, and tall, wine-coloured staircases, he stops at a large table. On it lie four yellowed sheets of paper, larger than standard notebook paper, each holding a flattened dried plant specimen with labels and handwritten notes in faded ink. These ‘herbarium sheets’ contain ‘specimens’, the way Kew scientists record new plants. Each sheet provides a snapshot of the plant for study and analysis.

This is my first time viewing herbarium specimens in person, and I feel as giddy as I did as a little girl visiting See’s Chocolate Shoppe in Los Angeles. I feel as though I’ve entered a botanical shrine, the holy grail of coffee knowledge.

Aaron selected four samples for our discussion: two Coffea stenophylla and two Coffea liberica. He explained that the ‘herbarium label’ serves as the foundation of scientific study, akin to a map legend for plants. Written around each specimen are notes, most in English or French, about the plant’s ecology, elevation, and uses, along with the collector’s name and habitat markers.

Looking closely at a sheet, we discuss the difference between ‘variety’ and ‘cultivar’ for different kinds of Coffea arabica.

‘In the botanical world,’ says Aaron, ‘“variety” represents wild variants. We have one accepted variety in the Coffea genus: Coffea liberica var. dewevrei, also known as excelsa.’

‘Does this mean that most of the ‘varieties’ we speak of in the coffee industry are not actually varieties?’ I ask.

‘Not scientifically,’ he confirms. ‘“Cultivar”, which derives from “cultivated” and “variety”, is more precise and represents the best-practice scientific terminology for cultivated plants.’

Shaking his head, he adds, ‘However, in the coffee industry, “variety” is so deeply embedded in both public and academic vernacular that advocating for “cultivar” over “variety” is a lost cause.’

My odyssey continued at the Kenya National Archives, where I discovered farming and colonial history absent from my former classrooms. While the birthplace of Coffea arabica is Kaffa, in southwestern Ethiopia, coffee didn’t arrive in East Africa until the late 19th century. Specific accounts of its arrival in what is now the Republic of Kenya are both contested and conflicting.

However, written records confirm that the British-controlled East India Company acquired arabica seedlings in Aden, Yemen, and sold them to French missionaries cultivating coffee on Bourbon Island (now Réunion). By 1817, this island was producing 3,000 tonnes of coffee annually. Throughout the 19th century, both Protestant and Catholic missionaries experimented with coffee seedlings and cultivation to fund their East African missions while growing subsistence crops for food. By the 1880s, many missions in Tanganyika (now Tanzania) had adopted coffee planting. In Kenya, a Catholic church established in the early 1890s near Mombasa—considered the oldest Catholic church in the country—also experimented with coffee cultivation. Records indicate that the first Kenyan coffee was planted in the Teita Hills (now Taita Taveta County) at the Bura Mission, likely established by the first Christian missionaries to the area in 1891. However, other records attribute the introduction of the ‘Mocha’ seed (Coffea arabica) to Scottish missionaries who brought it from Aden to Kenya in 1893, near present-day Nairobi.

Not far from downtown Nairobi, priests at the first Catholic parish in inland Kenya, founded by the Congregation of the Holy Ghost Fathers in 1899, experimented with coffee. Later known as St Austin’s, this mission is referenced in several writings by colonial settlers as the source from which they purchased coffee seedlings, including those of Karen Blixen. The Coffee Board of Kenya honoured this parish with a stone plaque at its entrance, commemorating the centennial of the planting of the first coffee tree in Kenya.

Regardless of which priests introduced Coffea arabica to British East Africa, coffee quickly became a vital source of profit for the British colonial government, as missions controlled the purchasing and development of seeds. Consequently, the cultivation of coffee (and tea) was promoted as a lucrative ‘tool of empire’ (I phrase I borrow from Erika Rappaport’s 2017 book A Thirst for Empire: How Tea Shaped the Modern World), attracting thousands of European settlers to British East Africa following the completion of the Uganda Railway in 1901 and the enactment of the Crown Land Ordinance in 1902, which allowed the British Colonial Government to claim all land they deemed unoccupied. As a result, vast areas of indigenous trees were cleared for cash crop farming, particularly coffee.

Scott Labs: the beginning of Kenya-bred varieties

By the 1910s, coffee farming had emerged as an important cash crop in several British-occupied territories in East Africa and Asia. However, coffee diseases were wreaking havoc on crops. One of the most destructive was the outbreak of Hemileia vastatrix, or coffee leaf rust, which occurred in the 1870s in British-owned Ceylon (now Sri Lanka). This notorious fungus, recognizable by its orange spots on the undersides of leaves, nearly eradicated the island’s coffee to the extent that its final harvest was in 1900. Subsequently, the British colonial government replaced all coffee with tea.

Little was known about how these diseases might affect East Africa until the establishment of Scott Labs. Founded in 1912 as a sanatorium for white settlers in Kenya, it was named after Rev. Dr Henry Edwin Scott, a Church of Scotland medical missionary. In 1907, he was transferred to Kikuyu, then known as British East Africa, where he served as the head of the Church Mission. He died in Kenya in 1911.

Years later, the British colonial government repurposed the building into Scott Labs—officially the National Agricultural Research Laboratory—dedicated to researching various colonial crops. The first researcher appointed in 1908 was an entomologist, as insects posed a significant threat to agricultural production. By 1912, Hemileia vastatrix was reported in Kenya.

Over time, more land was needed for coffee research. In 1944, the colonial government acquired land in Ruiru to establish a coffee research station. This station, formerly the Coffee Research Foundation, was completed in 1949 with funding from colonial Britain. Today, it is known as the Coffee Research Institute (CRI), part of the Kenya Agricultural and Livestock Research Organization (KALRO).

No coffee trees bloom where the old Scott Labs once stood; it is now an unremarkable barracks-style building, obscured by a new, traffic-plagued highway across from a shopping mall.

Visiting Ruiru

To reach the CRI, navigate through Nairobi, characterized by metallic skyscrapers and dilapidated shantytowns bustling with small businesses. Drive north on Thika Highway and take a left onto an unmarked road. Continue straight, disregarding any feelings of being lost, and eventually turn left at the Coffee Research Institute sign. Upon reaching the gate, sign in, and you will find yourself flanked by miles of lush coffee trees, showcasing all of Kenya’s varieties.

Since Kenya gained independence in 1963, the centre has been led by Kenyan coffee scientists and researchers, among them Dr Cecilia Kathurima, who in 2008 began collecting data for her PhD, culminating in her dissertation titled ‘Characterization of Coffee Genotypes in Kenya by Genetic, Biochemical and Beverage Quality Profile’. She has since served as the Coffee Quality Manager at CRI, earning a reputation as a respected coffee scientist. Cecilia is passionate about the positive impact coffee can have in Kenya, providing a livelihood for over 800,000 farmers. As she says, ‘Coffee isn’t just a beverage, but a source of income that supports families and communities across our country.’ More than 75 percent of Kenya’s rural population depends on coffee income for their livelihoods.

Earlier this year, Cecilia and I drove past rows of French mission coffee trees, many planted in the 1950s, alongside older Blue Mountain trees. When she stopped at a lane of coffee trees, we got out of the car and saw a row representing all of Kenya’s varieties, each labelled with a painted block of wood bearing names like ‘SL34’ and ‘K7’. Some original Ruiru 11 was planted here in the early 1980s.

I felt like Willy Wonka in his chocolate factory, marvelling at the diverse species and cultivars while contemplating their significance for the future of Kenyan coffee.

After our walk, we proceeded to Cecilia’s Quality Lab, one of the two dozen buildings on that side of the property. We discussed the origins of the SL series of coffee, originally bred at the Scott Labs. Cecilia explained, ‘Scientists for the British colonial government planted 42 trees to assess their yield, quality, and disease resistance,’ noting that at that time, ‘the diseases were not as prevalent as they are now.’ From the best-performing trees, samples were taken, resulting in the now-famous SL 28 and SL 34 varieties, released in Kenya before the 1940s.

From the outset, SL’s strength lay in its quality, but its major drawback has always been its high susceptibility to coffee berry disease (CBD) and coffee leaf rust (CLR).

As Cecilia explained, the need for improved coffee varieties is linked to challenges posed by coffee’s adversaries, particularly Hemileia vastatrix. This fungus threatens coffee production in Kenya and has spread to higher-altitude regions. Since the first known epidemic of CLR in Ceylon in 1869, it has infiltrated every major coffee-growing region worldwide. Notably, CLR caused yield losses of up to 50 percent during the 2013 harvest season in South America and the Caribbean.

Shortly after Kenya’s independence in 1963, the property in Ruiru was renamed the ‘Coffee Research Foundation’ in 1964. At that time, four main arabica varieties were planted in Kenya: French Mission, K7 (brought from India), and SL 28 and SL 34, developed at Scott Labs.

Making coffee babies: Ruiru one-one

Breeding efforts continued through the 1970s, with hybrid variety testing expanding in the early 1980s. Ultimately, Ruiru 11—named after its development site—was introduced in 1985. While ‘eleven’ is often used conversationally, it is not scientifically correct. As Cecilia clarifies, ‘It’s not really eleven; it’s one-one. Ruiru is a hybrid, a one-way cross between two designated parent plants.’ The mother plant is Catimor, known for its resistance to CBD and CLR, while the father plant comes from elite arabica crosses.

At the Ruiru station, there are separate plots for the mother and father plants—two distinct seed gardens. When scientists are ready to fertilize, they first emasculate the flowers of the mother plants by removing the male parts. They then collect pollen from the father plants, and the artificial insemination process follows.

This procedure must be conducted when the buds are open. Scientists twist each flower to detach it and take the male flowers to the lab, where they brush off and store the pollen in small vials. They then return to the mother seed garden with the pollen and a small brush to apply it to the female parts of the flowers. Once this is done, they cover that part of the branch to prevent other pollen or bees from fertilizing the coffee. Finally, the entire tree must be isolated and covered.

‘Why must the mother, Catimor, be emasculated?’ I ask.

Cecilia responds, ‘Since arabica is self-pollinating, we need to prevent it from fertilizing itself or anything else when it matures. It’s essential to act before the bud opens, ideally within four days. If we miss that window, fertilization may have already occurred.’

‘Is it like the small window of time in a female human when an egg can be fertilized by sperm?’ I ask.

‘Yes, we must go early in the morning to resurrect the father.’ Smiling, Cecilia affirms, ‘We are making babies—and the most challenging one to make is Ruiru 11.’

The result is hybrid vigour with a high yield. Since its introduction in Kenya in 1985, the demand for certified Ruiru has far exceeded what CRI can supply. To be authentically Ruiru 11, the seeds must come from CRI or other certified nurseries in Kenya. Producing Ruiru 11 is a difficult, costly, and time-consuming process, requiring meticulous hand labour—and therefore, funding.

Batian: the peak of coffee excellence

Breeding is ongoing, and from 1985 to 2010, coffee scientists worked to produce a resistant variety that doesn’t require hand pollination. This effort led to the creation of Batian, Kenya’s newest variety. Ultimately, five lines of coffee were evaluated over time by CRI. For a new variety to be released, it must be distinct, uniform, and stable. Three lines met these criteria and were accepted.

This was a significant achievement because, unlike Ruiru 11, the three lines were resistant to leaf rust and coffee berry disease. More importantly, they were ‘true to type’, meaning farmers could harvest berries, plant them, and produce coffee that genetically resembles its parent—essentially, coffee that is Batian. Cecilia’s job focused on the sensory and biochemical aspects of what would become Batian. She compared the new lines with existing varieties and examined their quality, while another researcher concentrated on disease resistance. She was also part of the naming committee, which chose the name ‘Batian’ after one of Mount Kenya’s highest peaks.

‘The idea was that this coffee would represent the peak of excellence, better than all other varieties,’ recalls Celia. Batian was officially released in 2010.

To gain insight into the practical aspects of both new coffee varieties, I visited Sheila Wahome at her family farm in Nakuru County. She owns and manages a stunning estate, Bahati Blue, which features both indigenous and shade trees, including macadamia, avocado, and mango, alongside thousands of Batian and Ruiru 11 coffee trees. These were planted simultaneously about 12 years ago but are kept separate on either side of Sheila’s house. While both varieties thrive with proper farm management, Sheila notes that Ruiru typically appears bushier, is often more productive, and slightly more resistant to weather and disease.

‘The trees are confused now,’ Sheila told me during my visit. In previous years, Kenya experienced severe droughts, resulting in considerable losses. ‘All the berries were on our trees. They were there, but we had to abort them and strip them off to save the tree. You must almost kill it for it to start again,’ Sheila explained.

Lifeblood

In 2023, coffee was Kenya’s fifth-largest foreign exchange earner. Understanding and managing CLR has become a focal point of international collaborative research, with the CRI in Kenya playing a vital role in this effort as its breeders continue to work tirelessly on new possibilities.

Throughout my journey to learn more, I reflected on Robin Wall Kimmerer’s words words from her book Gathering Moss: ‘In indigenous ways of knowing, all beings are recognized as non-human persons, and all have their own names. It is a sign of respect to call a being by its name, and a sign of disrespect to ignore it.’ Despite the many names assigned to Kenya’s land and coffee, our arabica varieties may diminish with age unless we take action to preserve both the coffee seed and the people who nurture it.