x polycaulis Bramw. & Rowl., 1973
Parentage : Monanthes polyphylla Haworth x M. subcrassicaulis Praeger
Monanthes x ploycaulis Bramwell & Rowley, Some name changes in succulent plants, Part V, National Cactus and Succulent Journal 28(1): 5. 1973.
Distribution : Canary Islands : La Gomera (Valle Hermoso).
Description by Praeger, Semperviva of the Canary Islands area in Proc. Roy. Irish Acad. Sect. B, 496 (1929) :
"Caulis repens ut in polyphylla sed crassior et laxiore ramosus, ramis adscendentibus ramulos multos emittentibus.
Folia inter parentes media, obovata, brevissime petiolata, 12 - 15 mm longa, 5 - 6 mm lata.
Rami floriferi ex centro rosularum, breves ut in polyphylla."
Description, also by Praeger, in An account of the Sempervivum Group, 242 (1932) :
"Intermediate between the parents.
Stem creeping as in polyphylla, but less slender and less branched, with ascending branches which branch frequently.
Leaves obovate, very shortly stalked, to 15 mm long, 5 - 6 mm wide.
Flowering branches short, from the centre of the rosette."
Praeger : "As in the case of others of these rather difficult hybrids, it is not easy to express in words the distinct appearance of this plant ; even when on the ground the parentage of the hybrid is clear, when viewed in relation to the possible parents growing on the island - icterica, laxiflora, pallens, polyphylla, subcrassicaulis. The present hybrid had just the dark purplish-green tint of subcrassicaulis."
Note :
Monanthes x polycaulis is a doubtful taxon. Praeger reports it from La Gomera, however – according to Bañares (2008) M. polyphylla – one of its parents - is limited to Gran Canaria and Tenerife.
Bañares wrote :
« Our study of plants from several locations in La Palma and La Gomera revealed the occurrence of Monanthes polyphylla subsp. amydros on both La Palma and La Gomera, whereas subsp. polyphylla is not present on La Palma. M. subcrassicaulis from those islands (Praeger 1932; Sventenius in sched., see Representative specimens) corresponds to subsp. amydros. Plants of subsp. amydros on La Palma are found outside the range of other representatives of the genus, along some eastern ravines above 600 m (Barranco del Carmen, Barranco de la Madera, Barranco de Río) and several northern and central locations (common inside Taburiente National Park at Roque de los Cuervos and La Cumbrecita). Our examination of plants collected in the type locality of Sempervivum monanthes var. filicaule Kuntze (La Palma, Barranco del Carmen) also revealed that Kuntze’s plant corresponds to M. polyphylla subsp. amydros. M. polyphylla subsp. polyphylla is confined to Gran Canaria and Tenerife, or probably only to Tenerife, since on Gran Canaria it may have been extinct since 30 years (Kunkel 1977) as our search for M. polyphylla in Gran Canaria was in vain, too.» (Taxonomic and nomenclatural notes on Crassulaceae of the Canary Islands, Spain, Willdenowia 38(2) : 475-489, 2008)
Conclusion :
1. M. polyphylla ssp. polyphylla, one of the supposed parents of M. x polycaulis, is not at all present on La Gomera where the latter has been found growing ; present on La Gomera is only M. polyphylla ssp. amydros.
2. The other parent, M. subcrassicaulis as found on La Gomera, is identical with M. polyphylla ssp. amydros.
3. That means, the parentage suggested by Praeger is not possible, and what he considered to be a hybrid is identical with the species M. polyphylla ssp. amydros.
4. Monanthes x polycaulis Bramwell & Rowley (1973), however, has been validly published and will still exist as a valid taxon for any hybrid of M. polyphylla x M. subcrassicaulis even if the hybrid will never be found in nature.