'Plinio', Ports Down, UK.
|Hybrid parentage||'Plantyn' × U. pumila 'S.2'|
|Origin||IPP, Florence, Italy|
Ulmus 'Plinio' is a hybrid elm cultivar derived from a crossing of the Dutch cultivar 'Plantyn' (female parent) with the Siberian Elm Ulmus pumila clone 'S.2'. It was raised by the Istituto per la Protezione delle Piante (IPP), in Florence and released for sale in 2003.
In Italy, 'Plinio' is a rounded tree with a broad crown, the width typically equalling 70% of height, and a short, often bent, trunk. The dark-green leaves are < 6.5 cm long by 3 cm broad and glabrous on both sides, on < 6 mm petioles. Like its compatriot 'San Zanobi', the tree is not possessed of striking autumn colours, the leaves remaining green almost until they fall in late November. The perfect, apetalous wind-pollinated flowers appear in mid March in the UK. The sessile samarae are round, and range from 17 mm to 22 mm in diameter. Seed has exhibited a modest viability of between 10% and 20%.
Pests and diseases
'Plinio' has a very high resistance to Dutch Elm Disease. In trials conducted by the Istituto per la Protezione delle Piante, Florence, 'Plinio' sustained 7.8% defoliation and 3.9% dieback when inoculated with unnaturally high concentrations of the fungal pathogen, compared with 4.7% / 0.0% resp. for 'Morfeo', 50% / 35.5% resp. for 'Lobel', and 95% / 100% for 'CNR118', a Field Elm (Ulmus minor) native to Italy. 
Fast growing (though slower than its stablemate 'San Zanobi') in Italy, where it commences flowering in its third year. The tree is only commercially available outside Italy by mail order. It was introduced to the UK by Butterfly Conservation in 2003 and is being evaluated at several sites in Hampshire, where it has been found to be particularly successful on thin dry rendzinas, however on more fertile soils, its relatively sparse and splaying top growth often exceeds stem and root development, necessitating judicious pruning and stake support for up to five years. 'Plinio' is not known (2013) to have been introduced to North America or Australasia.
- Grange Farm Arboretum, Sutton St. James, Spalding, Lincs. UK. Acc. no. 694.
- Great Fontley Farm, Fareham, UK, Butterfly Conservation Elm Trials plantation, Home Field B1, J2, J6, (planted 2004).
- Royal Botanic Garden Edinburgh, UK. Acc. no. 20042083
- Sir Harold Hillier Gardens, UK. Acc. no. 2004.0936
- Santini A., Fagnani A., Ferrini F. & Mittempergher L., (2002) 'San Zanobi' and 'Plinio' elm trees.  HortScience 37(7): 1139-1141. 2002. American Society for Horticultural Science, Alexandria, VA 22314, USA
- Santini A., Fagnani A., Ferrini F., Mittempergher L., Brunetti M., Crivellaro A., Macchioni N., Elm breeding for DED resistance, the Italian clones and their wood properties.  Invest Agrar: Sist. Recur. For. (2004) 13 (1), 179-184. 2004.
- Brookes, A. H. (2012). Disease-resistant elm cultivars, Butterfly Conservation trials report, 2nd revision, 2012. Butterfly Conservation, Hants & IoW Branch, England.