According to a German Yucca friend should there exist a sport" of this hybrid were named Yucca 'Graebeneri'. If any of the readers know more about this please let me know.
Yucca xkarlsruhensis is a very good plant, surely hardy. It has narrower leaves -half than that of Yucca filamentosa quite similar to the leaves of many forms of Yucca arkansana, flowers a lot regularly. It has a dense head of leaves, and no stem.
In the original publication, Graebener (1903) had the foresight to include photos of both parents of his new hybrid (Yucca glauca as the pollen parent, and Yucca filamentosa as seed parent). But the plant he pictured as Yucca filamentosa L. is actually Yucca flaccida Haworth. And as you know Yucca flaccida has a long history of being misidentified as Yucca filamentosa in the horticultural trade.
Graebener may have had 3 seedlings that survived as mature plant's and it would be interesting to know what happened to all three, they were all distributed as Yucca X karlsruhensis. So there must be a little difference between the plants that are in cultivation? and the name must be invalid, while a cultivar name can only be given to one single clone!
According to Karl Räder (Obergartner Der Königlichen Gartenbaulehranstalt zu Budapest 1906) were there already some misunderstanding, here only 3 years after Graebener did publish his new Hybrid. Räder writes in Die Gartenwelt 10 (18): 214 (1906), that a photo was shown of one of these hybrids, in the Catalog of the 'Firma Haage & Smidt', Erfurt, page 223 (1906). But the leaves of the plant shown in the catalog are more like those of Yucca angustifolia (a synonym for Yucca glauca), with more narrow and a different color from what Yucca xkarlsruhensis should have?
I may be on the track of one the "lost" clones of this hybrid, while the late nursery owner P.C.O. Nørgaard, Sundby Mors (deceased 2003), may had found one of the lost clones, and I got a cutting of it in the summer of 2000. He did cultivate the plant under the name Yucca "Karlsruhensis Type 2"
Yucca "Karlsruhensis Type 2" (Yucca flaccida X Yucca glauca )
There are plants distributed in Europe, which are propagated from seeds, and those must be considered as F:2 hybrids and are NOT "real" Yucca xkarlsruhensis! and they do not look anything like the original clone of Yucca xkarlsruhensis! Seeds and seedlings of Yucca xkarlsruhensi should be labeled as Yucca EX xkarlsruhensis F2.
This plant is one of the most wanted Yucca hybrids when people visit our garden and has hope it could be available to more people. I in 2002 I did make a joint-venture with Robert Wellens from the Dutch tissue culture laboratory: Succulent Tissue Culture and he did try to Yucca hybrid in-vitro, but unfortunately did he not have succes with the Yucca "Karlsruhensis Type 2". But he did have succes with propagating the F2 Yucca "Karlsruhensis Type 2" which now is available from Succulent Tissue Culture.
Yucca 'Karlson' in-vitro at Succulent Tissue Culture, The Netherlands.
Copyright 2004-2006 Robert Wellens.
Photos from September 18th. 2004.
My own plants of Yucca xkarlsruhensis
2062 Yucca xkarlsruhensis, small cutting received in 2008 from Karsten Horn Germany, originating from Karlsruhe botanical garden, this should be the same clone as in Graebener's article from 1903 (GRAEBENER, Die Gartenwelt
2432 Yucca xkarlsruhensis, small cutting from Sascha Weissbeck 2010.
1168 Yucca "Karlsruhensis Type 2"F:2 = probably a seedling of Yucca xkarlsruhensis! This one has now been given the name Yucca 'Karlson', and is availiable from Succulent Tissue Culture, The Netherlands.
2360 Yucca EX xkarlsruhensis F2 seeds of Yucca xkarlsruhensis, seeds from Alexander Heim 2010.
2436 Yucca EX xkarlsruhensis F2 seeds of Yucca xkarlsruhensis, seeds from Sascha Weissbeck 2010 sown 2011.
1454 Yucca "Karlsruhensis Type 2". From Zagreb botanical garden.
8 (1): 7, fig. (1903) (opens in PDF from Gartentexte digital)).
Die Gartenwelt 8 (1): 7, fig. (1903) (opens in PDF from
GRAEBENER, Die Gartenwelt 10 (7): 83, fig. (1905) (opens in PDF from Gartentexte digital)
TAROUCA, Freiland-Laubgeholze 377, abb. 494 (1913);
SCHNEIDER, New Flora & Silva 1:34-35, fig. 10 (1928);
Moeller's Deutsche Gartner-Zeitung 50: 296, fig. (1935)
BEAN, W.J., Trees and Shrubs, Hardy in the British Isles. pg. 765.
SCHACHT, W. & FESSLER, A., Die Freiland Schmuckstauden. pg. 674.
REHDER, A., Manual of Cultivated trees and shrubs, hardy in North America. pg. 898-899,
Räder, Karl. Die Gartenwelt 10 (18): 214 (1906). (opens in PDF from Gartentexte digital)
PEDERSEN, P.B., Kaktus 21(4):81 1986
SYDOW, G., Kaktus 12(2):34 (1977) Yucca (Liliaceae)
SYDOW, G., Kaktus 12(2):33 (1977) fig.
Special thanks to Mark van Zwet, whom has helped me finding, very important information about this interesting hybrid.
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