Olea europaea subsp. europaea

Where it comes from

Careful here, because the species range is a trap. Kew gives Olea europaea as native across Africa and the Mediterranean to south-central China — 55 regions.¹ But almost all of that belongs to the African and Asian subspecies. The cultivated olive is subsp. europaea, and its native range is the Mediterranean basin alone: eighteen regions, Albania to Türkiye.² A page saying an olive is native to China would be traceable to Kew and practically nonsense.

Domestication is contested in an interesting way. One study places the primary centre in the northern Levant, with three pre-Quaternary lineages and refugia in the Near East, the Aegean and Gibraltar.³ Another, working from 387 accessions, finds three gene pools with the central Mediterranean one showing admixture with wild olives — which points to local domestication events as well.⁴

Naming and description

Linnaeus, Species Plantarum, 1 May 1753.¹⁵ Kew accepts eleven species in the genus and, for O. europaea, seven subspecies and no varieties at all — I checked the taxon page myself.⁶¹ So the “var. europaea” you see written is not a name Kew recognises, and the wild olive names — var. sylvestris, Olea oleaster, Olea sativa — are all synonyms of subsp. europaea.⁷ The oleaster-versus-cultivated-olive distinction is real genetically and horticulturally; it is just not a taxonomic rank.

Fun facts

• Cold is a requirement, not a tolerance — and warmth actively erases it. This is the most useful thing on the page. Flowering is initiated by accumulated chilling: chill banks roughly between 41 and 60 °F (5-15.5 °C) and needs about thirteen to fifteen weeks. Above 61 °F (15.9 °C) chill already accumulated is cancelled, with cancellation strongest at 69 °F (20.7 °C) and above.⁸⁹ So an olive in a living room at 68-72 °F (20-22 °C) is not accumulating slowly — it is running the counter backwards, all winter, every winter. That is why it never fruits, and no amount of feeding or light will change it.
• Fluctuating cold beats constant cold. A 1971 experiment found four hours a day at 70-79 °F (21-26 °C) enhanced chilling, twelve hours destroyed it, and a constant 54.5 °F (12.5 °C) induced flowering but prevented the pistil from developing — flowers that cannot set fruit.¹⁰ A cold greenhouse that warms in the sun is better than a cellar at a steady temperature.
• Nobody tells container growers any of this. I checked the RHS twice, Kew, NC State, Oregon State and UF/IFAS: none of them mentions chilling, vernalisation or a cold flowering requirement. The RHS gets there by observation instead, saying an olive may “sometimes in hot summers and southern gardens, reward you with a crop”, and its advice to overwinter somewhere frost-free happens to work — but only if that place is genuinely cold.¹¹
• Those thousand-year-old olive trees are mostly not. Radiocarbon work on a tree “estimated to be hundreds of years old” found the oldest datable material was under 200 years, with piths dating to roughly 1840-1920. Ring counts disagreed with radiocarbon by about twenty rings, and the trunk turned out to be multiple fused shoots with multiple piths — so measuring girth measures the wrong thing entirely.¹² Living olive wood is rarely older than 300 years. Kew describes its own olives as over a hundred years old.¹³
• Your own olives will be inedible, and the chemistry has a name. The bitterness is oleuropein, a secoiridoid glucoside of elenolic acid and hydroxytyrosol, with a bitterness threshold around 80 ppm and leaves carrying 60-90 mg per gram dry weight.¹⁴ Lye destroys it; fermentation converts it. Raw off the tree, it is not food.
• One tree is enough, if it ever flowers. UF/IFAS records ‘Arbequina’ as self-pollinating and ‘Mission’ as self-fertile,¹⁵ so pollination is the second problem here, not the first.