Aloe castellorum

Overview

Aloe castellorum is a stemless, usually solitary aloe with erect to spreading rosettes of glossy bright yellowish-green lanceolate leaves. Its shiny green leaves with small, closely set marginal teeth and its erect yellow-flowered inflorescences are emphasized as readily distinctive in the Arabian highlands. [1] [2]

Key characteristics

Growth form

Stemless; solitary or forming two to three rosettes by rosette dichotomy. [1] [2]

Leaves

The leaves are rosulate, lanceolate-acuminate and glossy bright yellowish-green. [2] [1]

Leaf surface

The upper surface is flattened, becoming slightly canaliculate toward the acute apex, and is unspotted or has only a few white spots. [1]

Leaf margin

The margins bear small deltoid teeth. [1] [2]

Inflorescence

The inflorescence is erect, with cylindrical to acuminate, subdensely flowered racemes. [1] [2]

Flowers

The flowers are glossy bright yellow; the perianth is cylindrical-trigonous, with outer segments free for 12–19 mm and apices spreading to slightly recurved, while open flowers are pendent. [1] [2]

Distribution

It is distributed in Saudi Arabia and Yemen. [3]

Habitat

It is reported from west-facing mountain slopes of the Great Arabian Escarpment, on crystalline Arabian Shield granites or sheet basalts of the Ethiopian Trapp series. Rainfall is described as occurring in two periods, in early spring and late summer. [1] [2]

Diagnostic features

Held sources relate Aloe castellorum to A. vacillans. A. castellorum is distinguished in the comparison by shiny bright green to yellowish-green smooth leaves and foggy west-facing slopes, whereas A. vacillans is described with glaucous, slightly rough leaves and reddish-brown marginal teeth. [2] [1]

Scientific name and synonyms

Accepted name: Aloe castellorum J.R.I.Wood [3] [1] [2] [4]
Synonym: Aloe hijazensis Lavranos & Collen. [3] [1] [4]
Publication: Kew Bull. 38: 25 (1983) [3] [1] [2]

Type specimen and type locality

McCoy (2019) cites the type as Yemen, Shaharah, 16°HN, 43°42'E, 22 September 1978, Wood 2S04, holotype K. [1] [4]

Taxonomic treatment

WCVP treats Aloe castellorum as an accepted species. [3] [1] [2] [4]

Epithet origin

The epithet castellorum means ‘of the castles’ and is linked to occurrence or preferred habitat on historic fortress mountains. [1] [4]

References

McCoy, T. (2019). The Aloes of Arabia. McCoy Publishing, Temecula, California. pp. 117–121.
Carter, S., Lavranos, J.J., Newton, L.E. & Walker, C.C. (2011). Aloes: The Definitive Guide. Royal Botanic Gardens, Kew. pp. 250–251.
World Checklist of Vascular Plants (WCVP).
Grace, O.M., Klopper, R.R., Figueiredo, E. & Smith, G.F. (2011). The Aloe Names Book. Strelitzia 28. South African National Biodiversity Institute, Pretoria. p. 32.