Cactaceae, Juss.

Walter, Helmut E. & Guerrero, Pablo C., 2022, Towards a unified taxonomic catalogue for the Chilean cacti: assembling molecular systematics and classical taxonomy, Phytotaxa 550 (2), pp. 79-98 : 80-81

The relevance of classifying the Cactaceae family into different subfamilies helps to better understand the subdivision into clades that differ morphologically (see key below).

On the other hand, the delimitation of some subfamilies has shown to been difficult (for example the paraphyly of the Pereskioideae K.Schum. and the ambiguous relationships of the Maihuenioideae P.Fearn with other subfamilies). Also, the tribes within the Opuntioideae K.Schum. and Cactoideae Eaton have undergone several changes, as molecular-based phylogenies provided new information about evolutionary relationships of its members. Most of the proposed changes at these taxonomic levels have an impact on the classification of Chilean cacti because the cactus flora in the Atacama Desert, the Altiplano, the Mediterranean area, and the Chilean Patagonian steppe harbours three of the four subfamilies and seven of the ten tribes.

1. Stems with functional leaves, at least on immature shoots; a 739 bp non-coding intron region in the chloroplast-encoded gene rpo C1 present .....................................................................................................................................................................................2

- Stems without functional leaves; a 739 bp non-coding intron region in the chloroplast-encoded gene rpo C1 is lost (subfam. Cactoideae ) .........................................................................................................................................................................................3

- Stems without functional leaves; a 739 bp non-coding intron region in the chloroplast-encoded gene rpo C1 is lost (Subfamily CACTOIDEAE ) ................................................................................................................................................................................10

2. Leaves persistent, terete; glochids on areoles absent; seeds without funicular envelope; stems astomatous, barky ... (subfam. Maihuenioideae ) .......................................................................................................................................................... 12. Maihuenia

- Leaves ephemeral, flat; areoles with spines and glochids; seeds encased in a funicular envelope; stems stomatous, bark formation delayed (subfam. Opuntioideae ).........................................................................................................................................................4

4. Branch segments flat to subterete; shrubs to 20 cm high .................................................................................................... 22. Tunilla

- Segments cylindric; shrubs to 1.5 m high ........................................................................................................... 14. Miqueliopuntia

3. Branches flattened to subterete or cylindric .........................................................................................................Tribe OPUNTIEAE

- Branch segments never flattened, terete in cross-section...................................................................................................................5

5. Shrubs to 60 cm high, then mound-forming; segments to 10 cm, with determinate growth; spines without sheath........................... .......................................................................................................................................................... TEPHROCACTEAE (pro parte)

- Shrubs to 1.5 m; branch segments to 30 cm, with indeterminate growth; spines with a papery sheath ( CYLINDROPUNTIEAE ) .. ............................................................................................................................................................................... 6. Cylindropuntia

6. Flowers dark red; petaloids few, <10; fruits 1cm, dark red, glabrous, pulp red................................ 21. Tephrocactus ( nigrispinus )

- Flowers not dark red; petaloids>10; fruits 2–5 cm, greenish yellow, not glabrous, pulp never red .................................................7

7. Seeds laterally compressed; perisperm large......................................................................................................................................8

- Seeds ± globose; perisperm small ......................................................................................................................................................9

8. Flowers immersed into apex; funicular girdle of seed formed into a papery wing.................................................... 17. Pterocactus

- Flowers not immersed; seeds not winged.............................................................................................................. 13. Maihueniopsis

9. Segments ±globose, etuberculate, easily detaching; spines on segments and fruits <5cm; areoles evenly distributed; fruits subglobose; seeds lack lateral ridges.................................................................................................................... 20. Sphaeropuntia

- Segments ±conical, tuberculate; not detaching; spines much longer; areoles crowded towards apex; fruits cylindric; lateral ridges present......................................................................................................................................................................5. Cumulopuntia

10. Hypanthium shorter than pericarpel; stems always cylindric ( PHYLLOCACTEAE subtribe CORRYOCACTINAE ) .................11

- Hypanthium longer than pericarpel; stems cylindric or not .............................................................................................................13

11. Plants low, branches 10–50 cm; central spines <4 cm; flowers with few small bracts; fruits 2-5 cm ...................... 1. Austrocactus

- Plants tall, 0.8–5 m; central spines longer, to 15 cm; flowers densely covered with large bracts; fruits 5–10 cm ..........................12

12. Flowers to 7 cm, whitish, narrow funnelform ................................................................................................................ 8. Eulychnia

- Flowers 8–11 cm, yellow, campanulate..................................................................................................................... 4. Corryocactus

13. Stems ±globose to elongating, small to medium-sized; flowers 1.5-6 cm; fruits never with pulp ..................................................14

- Stems cylindric, (subcylindric in Lobivia ferox ), mostly tall; flowers large, 7-18 cm; fruits with pulp or pulpless ( CEREEAE ) ...17

14. Fruit dehiscing apically, funiculi juicy at fruit maturity (seed ant-dispersed) (INCERTAE SEDIS).............................. 3. Copiapoa

- Fruit dehiscion not as above; funiculi dry at fruit maturity (seed not ant-dispersed) (Tribe NOTOCACTEAE )............................15

15. Flowers 2–7 cm, bract scales numerous, axils woolly and bristly; fruit always dehiscing basally (except for Eriosyce rodentiophila ) .................................................................................................................................................................... 7. Eriosyce

- Flowers small, to 2 cm, bract scales few, axils naked; fruit dehiscence lateral or basal ..................................................................16

16. Stems 1–3 cm, areoles subtended by tiny persistent leaf; fruits elongating to 3 cm, dehiscing basally .................... 18. Rimacactus

- Stems to 15 cm diam., leaf absent; fruits <1 cm, dehiscing laterally .............................................................15. Neowerdermannia

17. Flower scales large, fleshy, imbricate; axils naked; stems with densely branched crown (subtribe REBUTIINAE ).. 2. Browningia

- Flower scales small, not fleshy, not imbricate; axils with ± wool (subtribe TRICHOCEREINAE )................................................18

18. Flowers brightly carmine red, zygomorphic; fruits without pulp, dehiscing basally................................................... 6. Oreocereus

- Flowers never carmine red, actinomorphic; fruits, with pulp never dehiscing basally....................................................................19

19. Stamens inserted in a single series; fruits indehiscent.............................................................................................. 9. Haageocereus

- Stamens inserted in two series; fruits dehiscent...............................................................................................................................20

20. Plants> 0.5 m, branches columnar or thickly cylindric ....................................................................................................................21

- Plants <50(-70) cm, globose, elongating with age ................................................................................................. 11. Lobivia [ ferox ]

21. Plants ±branching, shrubby or treelike; flowers narrowly funnelform, whitish........................................................... 10. Leucostele

- Plants usually unbranched, thickly cylindric; flowers campanulate, yellow............................................................... 19. Soehrensia

The comparison of the taxonomic classifications shows that there are important differences in the number of Chilean genera and species ( Table 1 ). Hunt’s classification (2006, 2013, 2016) includes the lowest number of species (95), whereas Rodríguez et al. (2018) reports the lowest number of genera (17). The percentage of endemic species also varies: 73% by Hunt et al. (2006, 2013, 2016), 74% by Rodríguez et al. (2018), 81% in the present study. These results highlight the importance of updating the taxonomic classifications in the Flora of Chile, because underestimating the endemism and number of species may have major negative effects on conservation (see e.g., Mace 2004, Duarte et al. 2014). The number of species accepted here means that the Cactaceae represent 6% of the Chilean native angiosperms and 5% of endemic species of Chile ( Rodríguez et al. 2018).