Presliophytum (Urb. & Gilg) Weigend, 2006

Acuña, Rafael & Weigend, Maximilian, 2017, A taxonomic revision of the western South American genus Presliophytum (Loasaceae), Phytotaxa 329 (1), pp. 51-68 : 58

Key to the species of Presliophytum

1. Herbs to sub-shrubs to 50 cm tall. Aerial structures not- to poorly lignified. Fruit with <100 seeds, each seed ca 1–2 mm long, testa transversally constricted. Restricted to northern Chile and western Argentina............................................................................... 2.

- Shrubs to 150 cm tall. Aerial structures lignified. Fruit with>1000 seeds, each seed ca. 0.5 mm long, testa foveate-reticulate. Restricted to Peru................................................................................................................................................................................. 3.

2. Plants annual to subperennial herbs. Leaves subentire, toothed to irregularly lobate. Sepals more than 3 × as long as wide. Nectar scales contrasting in color with the corolla. Fruit with>10 seeds. Restricted to the interior (more than 80 Km from the ocean) of northern Chile and western Argentina.................................................................................................................. P. malesherbioides

- Plants perennial subshrubs. Leaves always more or less regularly lobate. Sepals less than 2 × as long as wide. Nectar scales the same color as the corolla. Fruit with(3–)4(–6) seeds. Restricted to coastal (less than 20 Km from the ocean) northern Chile......... .................................................................................................................................................................................... P. sessiliflorum

3. Leaves reniform. Uniseriate glandular hairs abundant on young stems and leaves. Restricted to Departamentos de Áncash and Lima ..................................................................................................................................................................... P. heucheraefolium

- Leaves ovate. Uniseriate glandular hairs very rare or absent .......................................................................................................... 4.

4. Sepals almost as long as wide. Petals subequal in size to sepals. Restricted to coastal Departamento de Arequipa .......................... ..................................................................................................................................................................................... P. arequipense

- Sepals ca. 1.5-2 × as long as wide. Petals at least 1.5 × as long as sepals. Widely distributed in the Pacific slope of Peru (Departamentos de Piura to Moquegua) ......................................................................................................................................... P. incanum