Aeonium

x jacobsenii   Bramwell & Rowley, 1973

Par: Aeonium hierrense (R.P.Murray) Pit. & Proust × Aeonium palmense Webb ex H.Christ

[or Aeonium canariense (L.) Webb & Berthel. × Aeonium hierrense (R.P.Murray) Pit. & Proust when A. palmense is considered to be included in A. canariense. (Art. H.5.2)]

Sempervivum hierrense R.P.Murray × Sempervivum palmense (H.Christ) H.Christ, Praeger, Notes on Canarian and Madeiran Semperviva, Transactions of the Botanical Society of Edinburgh 29: 200. 1925 nom. nud.

Aeonium hierrense (R.P.Murray) Pit. & Proust × Aeonium palmense H.Christ, Praeger, Semperviva of the Canary Islands area, Proceedings of the Royal Irish Academy 38 Sect.B (1): 475, t.11, fig. 12. (24 Sep) 1929.

Aeonium ×jacobsenii Bramwell & G.D.Rowley, in Jacobsen & Rowley, Some name changes in succulent plants, Part V, National Cactus and Succulent Journal 28(1): 5. (Mar) 1973.

Etym: Named for Hermann Johannes Heinrich Jacobsen (1898-1978).

T: Islas Canarias, Hierro, widespread around the north coast; 1924, R. Lloyd Praeger.

HT: Sketch of leaf, in Praeger, Semperviva of the Canary Islands area, Proceedings of the Royal Irish Academy 38 Sect.B (1): 475, t.11, fig. 12. (24 Sep) 1929.

Obs: In Bañares (Vieraea 43: 193, 2015), Art. 40.1 (lack of type) is cited as a reason for a superfluous reneotypification, but Praeger's sketch was referred to in the validation by Bramwell & Rowley as “1929: 475”, the place of publication of the protologue description, where there is also a reference to the illustration as “Plate XI, fig. 12”. This is the only included element of Praeger's description and thus also of Bramwell & Rowley's validation.

Description (according to Praeger, An Account of the Sempervivum Group, 1932 :

Monocarpic, or more rarely branched and perennial, erect, 60 cm high.

Stem thick, 2.5 cm in diameter, bare below.

Leaves in the barren plant in a large terminal rosette, bright green, glabrous or minutely pubescent, with elongate-deltoid cilia pubescent at the base, and with pubescence between the cilia.

Inflorescence intermediate, about 25 cm broad.

Flowers whitish or reddish or yellowish, intermediate in shape and size.

Flowering time : March.

Habitat : Canary Islands : Hierro, often abundant with the parents, 800 m.

The hybrid presents a great array of interesting forms, from the tall, unbranched, glabrous pink-flowered hierrense to the low, tufted, branched, densely pubescent yellow-flowered palmense.

 

 

Aeonium ×jacobsenii HT from Praeger, Semperviva of the Canary Islands area, Proceedings of the Royal Irish Academy 38 Sect.B (1): 475, t.11, fig. 12. (24 Sep) 1929.

 

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