Pilea, Lindley, 1821

Soares, Júlia Fialho & Miotto, Silvia Teresinha Sfoggia, 2023, Pilea bradei (Urticaceae), a new species from the Atlantic Forest Biome in Southeastern Brazil, Phytotaxa 584 (3), pp. 161-172 : 169

Key to the species of Pilea in the Atlantic Forest Biome, Southeastern Brazil

1. Plants with trichomes .........................................................................................................................................................................2

1. Plants without trichomes ....................................................................................................................................................................3

2. Lamina of the leaves with serrate margin, only the adaxial surface with trichomes; petioles with trichomes concentrated near the junction with the lamina ............................................................................................................................................. P. hyalina Fenzl

2. Lamina of the leaves with crenate margin, the abaxial and the adaxial surface with trichomes; petioles with trichomes distributed throughout its length..................................................................................................................................... P. pubescens (L.) Liebm.

3. Lamina of the leaves with entire margin ............................................................................................................................................4

3. Lamina of the leaves with crenate, crenate-serrate, or serrate margin ...............................................................................................5

4. Lamina of the leaves unequal in length by ratio 1:2.6–4, minor laminae 0.1–5 × 0.1–3 mm and major laminae 0.3–10 × 0.2–5 mm; nodes with predominantly more than one pair of leaves; staminate inflorescences sessile or with the peduncle up to 6 mm long. P. microphylla (L.) Liebm.

4. Lamina of the leaves equal to unequal in length at the same node by ratio 1:1.2–2, 3–17 × 2.2–9.7 mm; nodes with predominantly one pair of leaves; staminate inflorescences with the peduncle 4–10 mm long............... P. carautae M.D.M.Vianna & R.J.V.Alves

5. Lamina of the leaves with T-, Y-, or X-shaped cystoliths...................................................................................................................6

5. Lamina of the leaves without T-, Y-, or X-shaped cystoliths (or with only punctiform, fusiform, or linear cystoliths) ....................7

6. Leaves decussate; laminae in the same node unequal in length by ratio 1:1.3–4.4; margin with 3–7 teeth per cm, most teeth with convex-retroflexed, convex-concave, or convex-straight shape ........................................................................ P. astrogramma Miq.

6. Leaves opposite; laminae in the same node unequal in length by ratio 1:5–12; margin with 1–3 teeth per cm, most teeth with convex-convex, straight-convex, straight-concave shape ........................................................................................ P. rhizobola Miq.

7. Abaxial surface of the laminae without linear to fusiform cystoliths or with only over the primary veins, and with minor secondary and tertiary veins barely visible to the naked eye when dried; 3–8 major secondary veins in each side of the midvein .................... ................................................................................................................................................................................ P. hilariana Wedd.

7. Abaxial surface of the laminae with fusiform cystoliths over the veins and other parts of the surface, and with minor secondary and tertiary veins markedly visible to the naked eye when dried; 10–20 major secondary veins in each side of the midvein.................. .................................................................................................................................................................................... P. bradei Soares