Castilleae
Description
Trees or shrubs with the architectural model of Cook, dioecious or monoecious, without uncinate hairs.
Leaves alternate, spirally arranged (on the main branches) and distichous (on the lateral branches);
stipules fully to semi-amplexicaul.
Inflorescences on the lateral branches, unisexual, capitate, discoid to cup-shaped with an involucre of basally attached bracts, pedunculate or sessile, interfloral bracts lacking (? or structures derived from the perianth).
Fruit(s) forming a drupaceous whole with the perianth, with other flowers, or also with the receptacle;
seed large, without endosperm, testa with or without a thickened vascularised part, embryo longitudinally aligned, with thick, equal or subequal, sometimes unequal cotyledons, radicle short and apical.
Distribution
Neotropical present, South America present, Tropical Africa present, from Sri Lanka to the Pacific present, from the African continent to Madagascar and Yemen present
The tribe comprises six neotropical genera (see ) for which at present 54 species are recognised. The tribe is centred in South America. Two monotypic genera are palaeotropical: Antiaris ranging from the African continent to Madagascar and Yemen and from Sri Lanka to the Pacific, and Mesogyne confined to tropical Africa (see ).
Morphology
The tribe is characterised by the tree architecture described as the model of Cook (Hallé & Oldeman, Essai sur l’architecture et la dynamique de croissance des arbres tropicaux (1970) 110). The leaves on the stem and orthotropic branches are spirally arranged, and in the axils of each of these leaves plagiotropic branches are formed sylleptically. Inflorescences are borne on these branches, often on axillary short-shoots. The plagiotropic branches are abscised; the bases of the shed branches are conical leaving a depression in the stem. This model requires accessory buds which in the neotropical taxa are lateral but axillary in the palaeotropical genera (see ).
In the neotropical genera the involucre of imbricate bracts of the pistillate inflorescences covers the outer surface of the receptacle. In the palaeotropical genera the involucral bracts are more or less scattered on the lower part of the receptacle and concentrated in the uppermost part.
In the neotropical genera the involucre of imbricate bracts of the pistillate inflorescences covers the outer surface of the receptacle. In the palaeotropical genera the involucral bracts are more or less scattered on the lower part of the receptacle and concentrated in the uppermost part.