Hitherto Aeonium (sect. Leuconium) urbicum has been considered endemic to the islands of Tenerife and La Gomera (Canary Islands). A close morphological examination of the populations on both islands revealed clear differences in taxonomically significant features. These findings justify the recognition of the populations in S Tenerife as a new variety, A. urbicum var. meridionale, and the segregation of the populations on La Gomera as a new species, A. appendiculatum. The new taxa are described and illustrated, their relationships are discussed and a key to the single-stemmed taxa of A. sect. Leuconium is provided.
References
Á. Bañares
1990: Híbridos de la familia Crassulaceae en las Islas Canarias. Novedades y datos corológicos II. — Vieraea 18: 65–85. Google Scholar
Á. Bañares
.
1992:
Aeonium pseudourbicum sp. nov. (Crassulaceae), nuevo endemismo de Tenerife (Islas Canarias). — Anales Jard. Bot. Madrid 50: 175–182. Google Scholar
Á. Bañares
&
M. C. León
1997: The identity of Aeonium ciliatum (Willd.) Webb & Berth. (Crassulaceae). — Willdenowia 27: 143–146. Google Scholar
A. Berger
1930:
Crassulaceae. — Pp. 352–483 in:
A. Engler
&
K. Prantl
(ed.),
Die natürlichen Pflanzenfamilien 18a. — Leipzig. Google Scholar
D. Bramwell
&
Z. Bramwell
1990: Flores silvestres de las Islas Canarias. — Madrid. Google Scholar
F. Hallé
,
R. A. A. Oldeman
&
P. B. Tomlinson
1978: Tropical trees and forests: an architectural analysis. — Berlin, etc. Google Scholar
A. Hansen
1977: On Christen Smith's names of Canarian plants. — Bot. Macaronésica 3: 25–34. Google Scholar
K. Lems
1960: Botanical notes on the Canary Islands II. The evolution of plant forms in the islands: Aeonium. — Ecology 41: 1–47. Google Scholar
H.-Y. Liu
1989: Systematics of Aeonium (Crassulaceae). — Special Publ. Natl. Mus. Nat. Sci. Taiwan 3. Google Scholar
A. Marrero
1992: Evolución de la flora canaria. — Pp. 55–92 in:
G. Kunkel
(ed.),
Flora y vegetación del archipiélago Canario. Tratado florístico de Canarias 1. — Las Palmas de Gran Canaria. Google Scholar
T. H. M. Mes
1995: Phylogenetic and systematic implications of sequence variation of chloroplast and nuclear spacer sequences in the Macaronesian Sempervivoideae and related Sedoideae. — Pp. 30–44 in:
H.'t Hart
&
U. Eggli
(ed.),
Evolution and systematics of the Crassulaceae. — Leiden. Google Scholar
T. H. M. Mes
&
H. 't Hart
1995: The evolution of growth-forms in the Macaronesian genus Aeonium inferred from chloroplast DNA RFLPs and morphology. — Pp. 93–114 in:
T. H. M. Mes
,
Origin and evolution of the Macaronesian Sempervivoideae (Crassulaceae). — Utrecht. Google Scholar
L. R. Praeger
1929:
Semperviva of the Canary Islands area. — Proc. Roy. Irish Acad., Sect. B, 15: 454–499. Google Scholar
L. R. Praeger
1932: An account of the Sempervivum group. — London [Reprint: Pl. Monogr. Reprints 1, 1967, Lehre]. Google Scholar
F. A. Stafleu
&
R. S. Cowan
1985: Taxonomic literature, ed. 2, 5. — Utrecht, etc. Google Scholar
V. Voggenreiter
1974: Geobotanische Untersuchungen an der natürlichen Vegetation der Kanareninsel Tenerife. — Diss. Bot. 26. Google Scholar
