Species, Varieties and Terroir

Two species that matter

Coffea arabica accounts for roughly 55–60 % of world production in recent ICO statistics¹ and nearly all specialty coffee. It is self-pollinating and genetically narrow², grows best at roughly 1,000–2,200 m in the tropics³, and has roughly half the caffeine of robusta: around 1.2 % by mass, within a reported range of about 0.8–1.4 %⁴. Its flavour range — floral, fruit, sugar, acidity — is what specialty coffee is built on.

Coffea canephora (robusta) is hardier, higher-yielding, disease-resistant, and contains roughly twice the caffeine, in the region of 1.7–4 % depending on the source⁴⁵. It is more bitter, heavier, and often rubbery or woody. Traditional Italian espresso blends use a share of robusta for crema and punch⁴. "Fine robusta" exists and is improving, but it remains a different drink.

Liberica and Excelsa are minor species with unusual, smoky-fruity profiles, mostly grown in Southeast Asia and West Africa³.

The arabica family tree

Almost every cultivated arabica variety descends from two lineages that left Yemen in the 1700s²:

• Typica — the original; elongated beans, low yield, clean and sweet. Ancestor of Blue Mountain, Kona, Maragogipe².
• Bourbon — a mutation from Réunion; rounder beans, 20–30 % higher yield, more sweetness and complexity. Ancestor of Caturra, Pacas, SL28, Mundo Novo, Catuaí².

Common varieties you'll see on bags. Lineage and agronomic notes follow the World Coffee Research variety catalog²; the flavour descriptions are trade consensus³:

Altitude and density

Coffee grown higher matures more slowly in cooler temperatures, and the trade has long associated that slower maturation with denser, harder beans and higher acidity³. High-grown coffee (1,600 m+) is generally described as:

• denser — it resists extraction, tolerates hot water and fine grinds, and rarely over-extracts;
• more acidic and complex;
• graded higher — Central American grades like SHB ("strictly hard bean") and SHG literally mean "grown high"³.

Those are trade descriptions rather than measured relationships in our sources, so treat the brewing consequences as Cup Engineering practice. One measured piece: a 2016 grinding study found that beans of different origins and roast levels ground to different particle size distributions under identical settings, which is consistent with density affecting how a bean fractures⁶.

Low-grown coffee (below ~1,200 m) is softer, milder, and easier to extract. Brazil is the important exception: much of its coffee grows at 800–1,200 m on flat plateaus, and its chocolate-nut-low-acid profile is partly a product of that³.

The bean library in this app records a density score for each coffee, derived from stated altitude as a working proxy; the recipe matcher uses it to suggest temperature and grind adjustments.

Terroir

Soil, microclimate, shade, rainfall timing, and picking discipline all show up in the cup, but they are hard to separate from processing and variety. What the trade reliably reports³:

• Ethiopia — floral, citrus, tea-like (washed) or blueberry and wine (natural).
• Kenya — blackcurrant, tomato, intense bright acidity.
• Colombia — balanced, caramel, red fruit; enormous range.
• Central America — chocolate, apple, clean sweetness; Costa Rica and Guatemala especially.
• Brazil — nutty, chocolate, heavy, low acidity.
• Indonesia — earthy, herbal, full-bodied.
• Panama Gesha — jasmine, bergamot, peach; delicacy over power.

Origin is a starting point for expectation, not a guarantee. A natural Colombian and a washed Colombian from the same farm can taste more different from each other than from coffees a continent apart.