Umbilicus oppositifolius (Ledeb. ex Nordm.) Ledebour (1843: 176)

Smith, Gideon F. & Monro, Anna M., 2022, Notes on the nomenclature and taxonomy of Chiastophyllum and Umbilicus oppositifolius (≡ Cotyledon oppositifolia, ≡ Chiastophyllum oppositifolium) (Crassulaceae subfam. Sempervivoideae), Phytotaxa 564 (2), pp. 239-247 : 244

Umbilicus oppositifolius (Ledeb. ex Nordm.) Ledebour (1843: 176) .

Homotypic synonyms:— Cotyledon oppositifolia Ledeb. ex Nordmann (1837: 313) . Chiastophyllum oppositifolium (Ledeb. ex Nordm.) Stapf (1930: 316–317) .

Type:— ““ Caucasus ” (Nordmann 329 [LE])” fide Walker (2003: 366, as “ T ”, i.e., “(nomenclatural) type ”, see Eggli 2003: X) .

Taxonomic placement of Chiastophyllum and Umbilicus oppositifolius :—At present Chiastophyllum is usually treated as a section in Umbilicus , as U. sect. Chiastophyllum , with the genus included in the Telephium clade of Crassulaceae subfam. Sempervivoideae ( Eggli et al. 1995: 179, 191, Walker 2003: 364, Thiede & Eggli 2007: 97, Messerschmid et al. 2020: 893). Umbilicus sect. Chiastophyllum is monotypic, with U. oppositifolius the only included species. Umbilicus oppositifolius has fibrous roots, while the roots of all other species of Umbilicus are tuberous or rhizomatous. The leaves of U. oppositifolius are not peltate and are more or less ovate, whereas all its congeners have more or less peltate leaves with the leaf blades varying little from an orbicular outline ( Fig. 2 ) ( Smith & Figueiredo 2011).

The flowers of U. oppositifolius range from light to bright yellow and are carried in branched, arched inflorescences ( Fig. 1 ). Selected forms of the species are available in the horticultural trade.

Figures

FIGURE 1. The leaves of Umbilicus oppositifolius are more or less ovate and, unlike those of most species of Umbilicus, not peltate. Photograph provided by and © of Ray Stephenson, U.K. Reproduced with his permission.

FIGURE 2. The leaves of most species of Umbilicus, such as U. rupestris (Salisbury 1796: 307) Dandy (1948: 611) shown here as a lithophyte on a rock wall in central Portugal near the town of Serra de Santo António, are peltate, more or less round in outline, and have a navel-like depression in the centre (for which the genus was named). Photograph: Gideon F. Smith.