true-to-type varieties. The species itself has been divided into two subspecies, subsp. paradoxa and subsp. nilotica. The former is found at lower altitudes (up to 600 m and occasionally much higher, but always west of the Nile drainage basin), is more drought-resistant, and takes longer to sprout (up to five months).
Shea grows in the dry forests and savanna with a very marked dry season of 6-8 months. There are also periodic droughts that go on several years. It also occurs scattered in dry forests throughout the Sudano-Sahelian zone, but does not extend into coastal areas. It is a light-demanding species of open sites, mostly solitary, and over its principal ranges commonly forms pure stands.
Rainfall Shea is found in areas with 400-1,800 mm rainfall per year. However, the trees are most common and healthy where they receive 600-1,200 mm and where the dry season lasts no more than 8 months.
Altitude Shea grows generally at low altitude, although on Cameroon’s Adamaua Plateau it ascends to 1,200 m above sea level.
Low Temperature It grows in areas characterized by average annual temperatures of 24-32°C. The minimum is reported to be 21°C.
High Temperature Temperatures where shea is found commonly climb into the lower 40s.
Soil Shea occurs naturally on the dry slopes of the savanna zone, but not in alluvial hollows or land subject to flooding. It is found on various soil types but seems to prefer dry and sandy clay soils with a good humus cover. Nonetheless, it tolerates stony sites and lateritic subsoils, although its yields may not be great.