Arabica Coffee Varieties: Typica, Bourbon, Gesha, SL28, Pacamara, and the Genetics of Flavor

When a specialty coffee bag lists "Gesha" or "Bourbon" or "SL28" as the variety, it is communicating something specific about the genetic identity of the coffee you are about to drink, an identity that shapes its flavour potential as surely as the altitude at which it grew or the country in which it was farmed. Coffea arabica is a single species, but it encompasses enormous genetic diversity. The named varieties, also called cultivars when they result from deliberate breeding or selection, have distinct physical characteristics, yield potentials, disease susceptibilities, and, crucially, different flavour profiles that express themselves consistently across different growing regions when the agricultural conditions are comparable. Understanding the major arabica varieties is one of the most useful tools a coffee drinker can develop, both for making sense of specialty coffee menus and for understanding why some coffees cost dramatically more than others.

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The Genetics of Arabica: An Unusual Species

Coffea arabica is unusual among domesticated crop plants in being an allotetraploid: it has four sets of chromosomes (2n = 44) derived from two ancestral diploid species, Coffea canephora (robusta) and Coffea eugenioides. This hybridisation event occurred naturally in the forests of southwestern Ethiopia (and/or the Boma plateau of South Sudan, according to a 2021 genetic study by Scalabrin et al. published in Nature Plants) and produced a species with relatively low genetic diversity compared to the ancestral species, because all cultivated arabica descends from a small founding population. This bottleneck means that arabica is genetically vulnerable, with limited disease resistance, and that the flavor differences between varieties, while real and perceptible, occur within a relatively constrained genetic space compared to, for example, wine grape varieties.

The Scalabrin et al. (2021) study sequenced the complete genome of Coffea arabica for the first time, providing a molecular basis for the family tree of arabica varieties that had previously been reconstructed largely from morphological observation and geographic history. The study confirmed that Typica and Bourbon, the two foundational cultivated arabica varieties, diverged from a common Ethiopian/Yemeni ancestor, and that virtually all other named arabica varieties derive from one or both of them, or from crosses with wild Ethiopian populations.

Typica: The Foundation of Global Coffee

Typica is the variety from which most of the world's cultivated arabica is descended. It originated in Ethiopia, was brought to Yemen (where coffee cultivation was first documented as an agricultural practice, in the 15th century by Sufi monasteries in the mountains near Ta'izz), and then spread through Dutch colonial trade networks: to Malabar in India (1690s), to Java (1699), to the Amsterdam botanical garden, to Martinique via the French (1720, through the famous voyage of Gabriel de Clieu who transported a seedling from the Paris botanical garden), and from the Caribbean throughout Latin America.

Typica plants are tall and relatively low-yielding, with large elongated beans (Typica beans are among the largest-seeded arabica varieties) and an open canopy architecture. They are not disease-resistant and have poor tolerance for Hemileia vastatrix (coffee leaf rust). Their cup quality, when grown at appropriate altitude under good management, is considered a benchmark for clean, classic arabica flavour: balanced, sweet, mild, with delicate floral and fruit notes. Jamaican Blue Mountain coffee, one of the world's most famous and expensive coffees, is grown almost entirely from Typica selections. Kona coffee in Hawaii is also predominantly Typica-derived.

Named Typica selections with distinct characteristics include San Ramón (a dwarf Typica mutant discovered in Costa Rica), Pache Común (a Guatemalan dwarf Typica), and Kent (a Typica selection developed in India in the 1920s with some leaf rust tolerance).

Bourbon: Sweetness and Diversity

Bourbon is a natural mutation of Typica that developed on the island of Réunion (formerly called Bourbon Island, hence the name) after French missionaries introduced Typica plants there around 1715. The Bourbon mutation produces rounder, smaller beans than Typica, with higher density and generally higher potential sweetness and complexity than standard Typica. Bourbon was reintroduced to mainland Africa and then to the Americas in the late 19th and early 20th centuries, becoming the dominant variety in Brazil, Colombia, and Central America by the mid-20th century.

Bourbon occurs in several natural colour variants based on the colour of the immature cherry: Red Bourbon (the most common), Yellow Bourbon (a mutation producing yellow cherries at full ripeness, found primarily in Brazil, particularly in the Minas Gerais state), and the extremely rare Orange Bourbon. Pink Bourbon, found in Huila, Colombia, is a less understood variant that may represent a hybrid or a distinct mutation, prized for its exceptional sweetness and tropical fruit character. Cup of Excellence Colombia has seen Pink Bourbon lots score among the highest ever recorded in the competition.

Important Bourbon derivatives include Caturra (a natural dwarf Bourbon mutation discovered in Brazil around 1937, now widely planted across Central and South America), Catuaí (a 1949 hybrid of Mundo Novo and Caturra developed by the Instituto Agronômico de Campinas in Brazil), and SL28 (see below).

Gesha (Geisha): The World's Most Expensive Variety

Gesha is the most commercially significant specialty variety of the 21st century. The variety originated in the Gesha (or Gecha) region of southwestern Ethiopia, near the border with South Sudan, where wild population plants were collected by researchers. Seeds were collected in 1931 by a British officer and deposited in the Jimma research station; plants were later transferred to Costa Rica's CATIE (Tropical Agronomic Research and Higher Education Centre) in the 1950s. From CATIE, plants were distributed to Panama, where the Peterson family of Hacienda La Esmeralda planted Gesha in the Jaramillo area of the Chiriquí highlands.

In 2004, Hacienda La Esmeralda submitted a Gesha lot to the Best of Panama auction. The lot scored 95.10 points, at that time an unprecedented score, and sold for $21 per pound, a record at the time. Subsequent years saw La Esmeralda Gesha prices escalate dramatically: $130 per pound (2006), $350 per pound (2013), and at a 2019 auction, a natural-processed Gesha lot sold for $1,029 per pound, the highest price ever paid for coffee at auction at that time.

Gesha is identifiable by its distinctive elongated coffee cherry and bean, its tall open plant architecture, and above all its flavour profile. Gesha grown at high altitude (above 1,700 meters) typically produces cup notes of jasmine, bergamot, stone fruit, tropical fruit, and a tea-like delicacy that is genuinely unlike any other arabica variety. The flavour expression is altitude-dependent: Gesha grown below 1,500 meters loses much of its characteristic complexity. The variety is now grown in Panama, Colombia, Ethiopia, Costa Rica, Guatemala, Honduras, Peru, and Tanzania, though Hacienda La Esmeralda's Panama Gesha remains the reference standard.

SL28 and SL34: The Kenyan Legacy

SL28 and SL34 are varieties selected by Scott Agricultural Laboratories (the SL designation) in Kenya in the 1930s and 1940s as part of the colonial-era programme to identify high-yielding, quality-focused coffee varieties for Kenyan production. SL28 was selected from a variety brought from the Tanganyika region (now Tanzania), possibly related to Bourbon, while SL34 was selected from a plant found in a Kabete mission station, possibly with Typica influence. Both have become defining varieties of Kenyan specialty coffee and are among the most distinctive arabica varieties in the world.

SL28 produces the cup profile most closely associated with Kenyan coffee's reputation: intense blackcurrant and tomato acidity, full body, complex fruit notes, and a long finish. The variety is sensitive to coffee berry disease (CBD) and coffee leaf rust, which has complicated its cultivation in regions with high disease pressure. SL34 is similarly quality-focused but slightly less disease-susceptible than SL28, and both varieties are the reason that Kenya's Cup of Excellence competition and Kenya AA auction lots attract some of the highest prices in the African coffee market. Ruiru 11 and Batian (bred by the Coffee Research Institute of Kenya in 1985 and 2010 respectively) are disease-resistant Kenyan varieties that have been widely adopted for their agronomic advantages, though specialty buyers typically prefer SL28 and SL34 for cup quality.

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Pacamara: El Salvador's Giant

Pacamara is a hybrid variety developed in El Salvador in 1958 by the Salvadoran Institute for Coffee Research (ISIC) by crossing Pacas (a Bourbon mutation discovered in El Salvador in 1949) with Maragogipe. The resulting variety is remarkable primarily for its bean size: Pacamara produces some of the largest beans of any arabica variety, often classified as Maragogipe-sized or larger in screen size grading. Maragogipe itself is a natural giant-bean mutation of Typica discovered in Maragogipe, Bahia, Brazil, around 1870.

Pacamara's cup profile has been described as complex, bold, and sometimes controversial: at its best it delivers intense body, pronounced acidity, and complex fruit and chocolate notes. At its worst, grown under poor conditions or poorly processed, it can be harsh and astringent. The variety has attracted significant specialty market interest in El Salvador and Honduras, where producers have entered Pacamara lots in the Cup of Excellence and achieved strong results. El Salvador's Cup of Excellence competition, relaunched in 2021 after a period of hiatus, has consistently featured Pacamara in its top lots.

Maragogipe: The Elephant Bean

Maragogipe (also spelled Maragogype) deserves its own mention beyond its role as Pacamara's parent. The variety's exceptional bean size, often two to three times larger than standard arabica beans, has made it a specialty curiosity since its Brazilian discovery. Mexican Maragogipe, grown in Chiapas and Oaxaca at high altitude, has developed a following for its light-bodied, delicately flavoured cup, which some describe as elegant but others find thin. The variety's low productivity has made it commercially marginal, and most Maragogipe production today is small-scale and sold at significant premiums justified by novelty as much as quality.

Why Variety Matters: A Practical Guide

For coffee drinkers navigating specialty roaster offerings, variety information on a bag is a useful but not determinative signal. Gesha virtually always signals a high-price, high-expectation purchase likely to deliver floral, delicate complexity, whether from Panama, Colombia, or Ethiopia. SL28 signals likely Kenyan origin and the characteristic blackcurrant acidity of that growing tradition. Bourbon and its derivatives (Caturra, Catuaí) are reliable across most quality tiers because their cup performance is less altitude-dependent than Gesha. Typica in a Jamaican Blue Mountain context signals the classic, clean, mild cup that has defined that market for decades.

Variety interacts with processing method and altitude in ways that make isolated variety judgments unreliable. A Gesha grown at 1,200 meters and processed carelessly will be disappointing regardless of its genetic potential. A well-farmed, well-processed Caturra at 1,800 meters can outperform a neglected Gesha at the same elevation in cup quality terms. The variety is the genetic potential. The terroir and the farmer's craft are what realise it.

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