Saxofridericia, Schomburgk, 1845

Berry, Paul E. & Krahl, Amauri Herbert, 2017, A new species of Saxofridericia subgenus Acrotheca (Rapateaceae) from Amazonas State, Brazil, Phytotaxa 326 (4), pp. 284-288 : 288

Key to the species of Saxofridericia subgenus Acrotheca

1. Margins of the leaf blade, petiole, and upper keel of the leaf sheath notably spinose; mature leaf blades (4–) 6–10 cm wide, with conspicuous, transversely reticulate tertiary veins ............................................................................................................ S. aculeata

- Margins of the leaf blade, petiole, and leaf sheath entire (except in S. brasiliensis , where they can be entire or spinulose); mature leaf blades 1–4.5 cm wide, without finely reticulating tertiary veins ............................................................................................... 2

2. Flowering heads subspherical, with whole portions of the bracts persistent but then only perforated by the sepals and not adherent to the base of the receptacle after anthesis; lower Rio Negro basin within 200 km of Manaus, northern Brazil........ S. brasiliensis

- Flowering heads depressed-globose and wider along the axis of the flattened peduncle apex, the basal part of the bracts adherent to the receptacle after anthesis; upper Rio Negro basin of northernmost Brazil, southwestern Venezuela, and southeastern Colombia … .................................................................................................................................................................................................. 3

3. Leaf sheaths round in cross-section; petiole 1–2 times the length of the blade; blades 1–2 cm wide ............................. S. petiolata

- Leaf sheaths compressed or flattened in cross-section; petiole shorter than or equal to the blade, or lacking; blades 1–4.5 cm wide ................................................................................................................................................................................................... 4

4. Leaves with little or no petiole; peduncles smooth and evenly flattened; leaves with little or no obvious venation ......... S. inermis

- Leaves with petioles 15–35 cm long; peduncles longitudinally sulcate (at least when dried); leaves with evident venation............. ...................................................................................................................................................................................... S. colombiana