Pontecorvo's note appeaers on p504 of the booklet.
A white flowered form of Sempervivum arachnoideum, by Guido Pontecorvo in The Journal of the Royal Horticultural Society, Vol 98, part II, p504
- This material is held at
- ReferenceGB 248 UGC 198/7/2/91
- Dates of CreationNov 1973
- Physical Description76 pages
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