Cephalanthinae DC. (de Candolle 1830: 538)

Romero, Maria Florencia, Gonzalez, Ana Maria & Salas, Roberto Manuel, 2023, Sylvainia, a new monospecific genus within the subtribe Cephalanthinae (Rubiaceae, Naucleeae), Plant Ecology and Evolution 156 (1), pp. 85-111 : 85

Subtribe Cephalanthinae DC. (de Candolle 1830: 538)

Cephalanthidae Tribe Cephalantheae Kunth ( Humboldt et al. 1818: 379).

Cephalanthidae Tribe Cephalanthidae Havil. ( Haviland 1897: 21).

Type genus.

Cephalanthus L.

Description of the subtribe.

Shrubs, rarely small trees, mostly erect, exceptionally scrambling or climbing, scarcely to much-branched. Stipules interpetiolar entire. Leaves opposite or 3- or 4-verticillate, pseudopetiolate. Inflorescences terminal and axillary, frondose-bracteate or bracteate; partial inflorescences congested. Flowers homostylous, perfect or functionally imperfect, with stylar pollen presentation; corolla aestivation imbricate, colleters in corolla located externally at the interlobular sinuses ( Cephalanthus ), or absent ( Sylvainia ). Ovary 2-carpellar, carpels 1-ovulate, each ovule pendulous. Fruit dry ( Cephalanthus ), or fleshy ( Sylvainia ). Seeds with prominent or reduced aril, longer than the seed ( Cephalanthus ), with a reduced aril shorter than a third of the length of the seed ( Sylvainia ).

Genera.

The subtribe Cephalanthinae comprises two genera: the type genus Cephalanthus and the new genus Sylvainia (Table 1 ).