Kenya Coffee School

Coffee Agronomy & Extension Handbook

Week 1 – Foundations of Coffee Agronomy

Day 1: Coffee Species and Varieties

Module 5: Coffee Species and Varieties

Learning Objectives

By the end of this module, learners should be able to:

Define a coffee species and a coffee variety (cultivar).
Identify the major coffee species grown around the world.
Understand the botanical classification of coffee.
Compare the characteristics of Arabica, Robusta, Liberica, and Excelsa.
Describe the major coffee varieties grown in Kenya.
Select suitable coffee varieties based on agroecological conditions, market demand, and climate resilience.

Introduction

Coffee belongs to the genus Coffea, a member of the Rubiaceae (coffee) family. Scientists have identified more than 130 coffee species, most of which occur naturally in tropical Africa and Madagascar. However, only a few species are cultivated commercially.

The four best-known species are:

Coffea arabica (Arabica)
Coffea canephora (Robusta)
Coffea liberica (Liberica)
Coffea liberica var. dewevrei (Excelsa)

Together, Arabica and Robusta account for over 98% of global coffee production, with Arabica dominating the specialty coffee market.

Botanical Classification

Coffee is classified as follows:

Kingdom: Plantae
Division: Angiosperms
Class: Eudicots
Order: Gentianales
Family: Rubiaceae
Genus: Coffea

Coffee is a perennial evergreen shrub or small tree capable of producing cherries for many decades when properly managed.

Morphology of the Coffee Plant

A coffee tree consists of several important parts:

Root System

Coffee has a deep taproot supported by numerous lateral roots.

Functions include:

Anchoring the plant.
Absorbing water.
Absorbing nutrients.
Storing carbohydrates.

Healthy roots are essential for drought tolerance and high productivity.

Stem

The stem supports the entire plant and transports water and nutrients between the roots and leaves.

Branches

Coffee develops:

Primary branches
Secondary branches
Tertiary branches

Flowers and fruits are mainly produced on the lateral (primary) branches.

Leaves

Coffee leaves are:

Dark green
Glossy
Opposite in arrangement
Elliptical in shape

Leaves perform photosynthesis, producing the energy needed for flowering and fruit development.

Flowers

Coffee flowers are:

White
Highly fragrant
Star-shaped

Arabica is largely self-pollinating, while Robusta depends more on cross-pollination.

Fruits (Coffee Cherries)

Each cherry contains:

Skin (exocarp)
Pulp (mesocarp)
Mucilage
Parchment
Silver skin
One or two coffee beans

The beans are the seeds used for roasting and brewing.

Arabica Coffee (Coffea arabica)

Arabica originated in the highlands of Ethiopia and is regarded as the world’s finest coffee species.

Characteristics:

Accounts for approximately 60–70% of global production.
Self-pollinating.
Best grown at 1,000–2,200 metres above sea level.
Requires cool temperatures (18–24°C).
Produces superior cup quality.
Lower caffeine content than Robusta.
More susceptible to pests and diseases.

Typical flavour profile:

Floral aromas
Bright acidity
Sweetness
Fruit notes
Complex flavours
Smooth body

Kenya is internationally recognised for producing premium Arabica coffee.

Robusta Coffee (Coffea canephora)

Robusta originated in Central and West Africa.

Characteristics:

Cross-pollinating.
Thrives in warmer climates.
Grows from sea level to about 900 metres.
Higher yields.
Greater resistance to Coffee Leaf Rust and some pests.
Higher caffeine content.

Typical flavour profile:

Strong body
Earthy notes
Bitterness
Chocolate flavours
Lower acidity

Robusta is widely used in espresso blends and instant coffee.

Liberica Coffee

Liberica originated in West Africa and is cultivated on a smaller scale in countries such as the Philippines, Malaysia, and Liberia.

Characteristics:

Large tree.
Large leaves.
Large cherries.
Large beans.
High resistance to certain diseases.

Flavour profile:

Smoky
Fruity
Floral
Woody

Liberica represents less than 2% of global coffee production but offers valuable genetic diversity.

Excelsa Coffee

Excelsa is now classified as a botanical variety of Liberica.

Characteristics:

Tall-growing tree.
Excellent drought tolerance.
Adapted to variable climates.
Distinctive fruit characteristics.

Cup profile:

Tart acidity.
Fruity notes.
Complex aroma.
Light body.

Excelsa is often used in specialty blends to enhance flavour complexity.

Major Coffee Varieties in Kenya

Kenya has developed several internationally respected Arabica cultivars through scientific breeding.

SL28

Developed in the 1930s by Scott Agricultural Laboratories.

Characteristics:

Outstanding cup quality.
Excellent drought tolerance.
Deep rooting system.
Bright acidity.
Blackcurrant flavour.
High market demand.

Weakness:

Susceptible to Coffee Berry Disease and Coffee Leaf Rust.

SL34

Also developed by Scott Agricultural Laboratories.

Characteristics:

Excellent sweetness.
Full body.
High productivity.
Performs well in high rainfall regions.
Exceptional cup quality.

Weakness:

Susceptible to major diseases.

Ruiru 11

Developed to improve disease resistance.

Advantages:

Resistant to Coffee Berry Disease.
Resistant to Coffee Leaf Rust.
Early bearing.
Compact growth habit.
Suitable for high-density planting.
High productivity.

This variety is ideal for farmers with limited land.

Batian

Released by Kenyan coffee researchers to combine productivity, disease resistance, and cup quality.

Advantages:

Excellent beverage quality.
Resistant to major diseases.
Early maturity.
High yields.
Suitable for climate adaptation.

Batian is increasingly promoted as a sustainable variety for future coffee production.

Factors Influencing Variety Selection

Choosing the right variety depends on several considerations:

Altitude

Different varieties perform best at different elevations.

Rainfall

Rainfall influences growth, flowering, and disease incidence.

Soil Fertility

Deep, fertile volcanic soils support vigorous coffee growth.

Disease Pressure

Areas with frequent Coffee Berry Disease or Coffee Leaf Rust may benefit from resistant varieties such as Batian or Ruiru 11.

Market Demand

Specialty buyers often seek varieties with exceptional cup quality, while commercial markets may prioritize productivity and consistency.

Climate Change

Climate-resilient varieties are becoming increasingly important as temperatures rise and rainfall patterns become more variable.

Conservation of Coffee Genetic Resources

Protecting coffee genetic diversity is essential for the future of the industry.

Conservation efforts include:

Maintaining seed banks.
Conserving wild coffee forests.
Establishing research collections.
Breeding improved cultivars.
Preserving indigenous coffee species.

Ethiopia’s wild Arabica forests remain among the world’s most important reservoirs of coffee genetic diversity.

Coffee Species and Sustainable Agrifood Systems

Selecting the appropriate species and varieties contributes to:

Higher productivity.
Improved resilience to climate change.
Reduced pesticide use.
Better resource efficiency.
Improved farmer income.
Conservation of biodiversity.

Integrating suitable varieties with regenerative farming practices strengthens the sustainability of coffee production systems.

Kenya Coffee School Perspective

Kenya Coffee School promotes the principle that “the right variety in the right environment, managed with the right agronomic practices, produces exceptional coffee.”

Students are encouraged to understand both the scientific and practical aspects of variety selection, enabling them to advise farmers, establish nurseries, manage plantations, and contribute to the long-term competitiveness of Kenya’s coffee industry.

Summary

Coffee diversity is one of the industry’s greatest strengths. While more than 130 coffee species exist, Arabica and Robusta dominate commercial production. Kenya’s renowned cultivars—SL28, SL34, Ruiru 11, and Batian—demonstrate how scientific breeding can combine quality, productivity, and resilience. Understanding species and varieties is fundamental to successful coffee agronomy and sustainable coffee production.