Rhodocactus sacharosa

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Rhodocactus sacharosa
In cultivation in Fairy Lake Botanical Garden, China
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Cactaceae
Genus: Rhodocactus
Species:
R. sacharosa
Binomial name
Rhodocactus sacharosa
(Griseb.) Backeb.[1]
Synonyms[1]
  • Pereskia moorei Britton & Rose
  • Pereskia sacharosa Griseb.
  • Pereskia saipinensis Cárdenas
  • Pereskia sparsiflora F.Ritter
  • Rhodocactus saipinensis (Cárdenas) Backeb.

Rhodocactus sacharosa, synonym Pereskia sacharosa, is a species of flowering plant in the cactus family Cactaceae,[1] native from Bolivia and west-central Brazil to Paraguay and northern Argentina. Like all species in the genus Rhodocactus and unlike most cacti, it has persistent leaves. It was first described in 1879.

Description[edit]

Rhodocactus sacharosa grows as a small tree or a shrub, reaching 5–7 m (16–23 ft) high.[2] Mature stems develop bark and, like most other species of Rhodocactus, have stomata.[3] Like all species of Rhodocactus and unlike most other cacti, R. sacharosa has persistent leaves. These are very variable in shape and size, 3–12 cm (1.2–4.7 in) long and 2–7 cm (0.8–2.8 in) wide, often folded along the midrib, which is very prominent on the underside, and with obvious petioles. The areoles on the twigs have up to five strong spines, 1–4 cm (0.4–1.6 in) long, those on the trunks may have up to 25 spines, 3–3 cm (1.2–1.2 in) long. The flowers are various shades of pink and are either solitary or borne in small terminal inflorescences of two to four, each flower being 3–7 cm (1.2–2.8 in) across. The fleshy fruits are more or less globe-shaped or pear-shaped, 4–5 cm (1.6–2.0 in) long and wide, green or yellowish when ripe.[2]

Spines on a leafless stem

Taxonomy[edit]

The species was first described by August Grisebach in 1879 as Pereskia sacharosa.[4] The specific epithet sacharosa is a noun in apposition, derived from a vernacular name.[5] One explanation is that it is derived from the Quecha word sacha, meaning 'tree' or 'woods', hence 'tree rose' or 'woods rose'.[6] In 1966, Curt Backeberg transferred the species to the genus Rhodocactus.[4] However, this was not accepted by most botanists, and Rhodocactus was sunk into a broadly circumscribed Pereskia. Molecular phylogenetic studies from 2005 onwards suggested that with this circumscription, Pereskia was not monophyletic, and consisted of three clades.[7][8][3] In 2016, the genus Rhodocactus was revived for one of these clades, which included R. sacharosa.[3]

Distribution and habitat[edit]

Rhodocactus sacharosa is native to Bolivia and west-central Brazil southwards to Paraguay and northern Argentina.[1] It occurs at elevations of 1,000–2,500 m (3,300–8,200 ft) in the foothills of the Andes and the semiarid Gran Chaco region.[2]

References[edit]

  1. ^ a b c d "Rhodocactus sacharosa (Griseb.) Backeb.", Plants of the World Online, Royal Botanic Gardens, Kew, retrieved 2021-05-01
  2. ^ a b c Anderson, Edward F. (2001), "Pereskia sacharosa", The Cactus Family, Pentland, Oregon: Timber Press, pp. 570–571, ISBN 978-0-88192-498-5
  3. ^ a b c Asai, Issaku & Miyata, Kazunori (2016), "An Emendation of Rhodocactus, a Genus Segregated from Pereskia (Cactaceae)" (PDF), Journal of Japanese Botany, 91: 7–12, retrieved 2021-04-25
  4. ^ a b "Rhodocactus sacharosa (Griseb.) Backeb.", The International Plant Names Index, retrieved 2021-05-01
  5. ^ Grisebach, A. (1879), "Symbolae ad Floram argentinam", Abhandlungen der Königlichen Gesellschaft der Wissenschaften zu Göttingen, 24: 1–345, retrieved 2021-05-01, p. 141
  6. ^ Leuenberger, Beat Ernst (1986), Pereskia (Cactaceae), Memoirs of the New York Botanical Garden, vol. 14, Bronx, NY: New York Botanical Garden, p. 111, ISBN 978-0-89327-307-1, retrieved 2021-05-02
  7. ^ Edwards, Erika J.; Nyffeler, Reto & Donoghue, Michael J. (2005), "Basal cactus phylogeny: implications of Pereskia (Cactaceae) paraphyly for the transition to the cactus life form", American Journal of Botany, 92 (7): 1177–1188, doi:10.3732/ajb.92.7.1177, PMID 21646140
  8. ^ Bárcenas, Rolando T.; Yesson, Chris & Hawkins, Julie A. (2011), "Molecular systematics of the Cactaceae", Cladistics, 27 (5): 470–489, doi:10.1111/j.1096-0031.2011.00350.x, S2CID 83525136