Tacinga, Britton & Rose, 1919

Freitas, Juliana Gomes, Alves, Lania Isis Ferreira, Zappi, Daniela Cristina, Almeida, Erton Mendonça De, Peraza-Flores, Lizandro N., Amaral, Daniel Oliveira Jordão Do, Araújo, Daniel Bruno Pereira & Batista, Fabiane Rabelo Da Costa, 2021, Novelties in Cactaceae from Eastern Brazil: Adding two new species and one new nothospecies to Tacinga (Opuntioideae), Phytotaxa 490 (3), pp. 239-252 : 250-251

Key to species of Tacinga

1. Plants scandent, stem-segments 25–70 cm long, cylindric or slightly flat at apex ............................................................................2

- Plants erect, decumbent or creeping, stem-segments 3–22 cm long, usually flat ..............................................................................3

2. Stem-segments completely cylindric, reddish; flower segments yellowish to brownish, sometimes purplish, anthers darkening after anthesis, style longer than stamens, pericarp with glochids 0.3–0.4 cm long, areoles without woolly hairs ........... Tacinga funalis .

- Stem-segments cylindric, the distal ones flat toward apex, dark green or purplish, flower segments light green or whitish, anthers whitish green, style as long as the stamens, pericarp with glochids 0.1–0.2 cm long, areoles with woolly hairs ............................... ................................................................................................................................................................................... Tacinga braunii

3. Plants spiny.........................................................................................................................................................................................4

- Plants unarmed .................................................................................................................................................................................11

4. Stem-segments, pericarp and fruits with whitish prominent stomata, areoles densely spiny, spines radially arranged, 1–5 central spines ..................................................................................................................................................................................................5

- Stem-segments, pericarp and fruits without visible stomata, areoles scarcely spiny, spine perpendicular or inclined to stemsegments, only 1 central spine............................................................................................................................................................7

5. Stem-segments with podaria slightly raised, spines thin and up to 3.0 cm long, golden or yellowish, pericarp and fruits unarmed.. ............................................................................................................................................................................................................6

- Stem-segments without visible podaria, spines thick and up to 5.5 cm long, whitish tipped brownish, pericarp and young fruits spiny ..................................................................................................................................................................................... T. armata

6. Fruits with 20–30 seeds, pulp reddish ...................................................................................................................................... T. lilae

- Fruits with 6–15 seeds, pulp translucent or greenish ..................................................................................................... T. palmadora

7. Stem-segments orbicular or obovate, young stem-segments areoles with long hairs ........................................................ T. saxatilis

- Stem-segments oblong or subcylindric, young stem-segments areoles without hairs .......................................................................8

8. Stem-segments with thin acicular cylindric spines, fruits oblong......................................................................................................9

- Stem-segments with thick acicular cylindric spines, sometimes slightly flattened at base, fruits globose......................................10

9. Flowers with reflexed segments, fruits orangish with no color variation around areoles.............................................. T. × flammea

- Flowers with erect segments, fruits whitish with a green ring surrounding the areoles ..................................................... T. werneri

10. Stem-segments oblong (9–15 × 6–8 cm), spines erect................................................................................................... T. gladispina

- Stem-segments subcylindric (3–8 × 1.5–3 cm), spines contorted....................................................................................... T. × quipa

11. Plants creeping, stem-segments subcylindric, pericarpel areoles with reddish hairs................................................ T. subcylindrica

- Plants decumbent, stem-segments flat, pericarpel areoles without hairs ........................................................................ T. inamoena