This section displays an arboretum (tree collection) arranged in three concentric semicircular terraces, one for each continent crossed by the 40th parallel north, which passes through Castilla–La Mancha in the province of Guadalajara. Along radii perpendicular to the semicircular design, different tree species are aligned in groups of three which, belonging to the same genus, originate from Asia (upper terrace), Europe (middle terrace) and North America (lower terrace).

The genera represented in this radial arrangement include pines (Pinus), yews (Taxus), firs (Abies), cypresses (Cupressus) and junipers (Juniperus), representing the gymnosperms, as well as ashes (Fraxinus), maples (Acer), lindens (Tilia), Judas trees (Cercis), hackberries (Celtis), walnuts (Juglans) and horse chestnuts (Aesculus), representing the angiosperms..