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Cultivar 'Lewis & Clark' = Prairie Expedition™ Origin North Dakota State University Research Foundation, USA People also search for Ulmus 'Morton Plainsman' Vanguard | ||
The American Elm cultivar Ulmus americana 'Lewis & Clark' (trade name Prairie Expedition) is a relatively new development from the North Dakota State University (NDSU) Research Foundation breeding programme, released in 2004 to commemorate the 200th anniversary of the eponymous expedition [1]. The cultivar was cloned from a tree discovered in 1994 along the Wild Rice River south west of Fargo, ND., where all those around it had succumbed to Dutch elm disease; the tree remains in perfect health (2008).
Contents
Prairie Expedition was introduced to the UK in 2008 by Hampshire & Isle of Wight Branch, Butterfly Conservation, as part of an assessment of DED-resistant cultivars as potential hosts of the endangered White-letter Hairstreak.
Description
Prairie Expedition is distinguished in maturity by its broad umbrella crown and dark green foliage. [2] The clone grows moderately quickly, averaging an increase of > 1 m in height per annum when young, reaching a height of <17 m in 25 to 30 years [3]. The leaves are < 13 cm in length by 9 cm broad, coarsely-toothed, and with a 4 mm petiole.
Pests and diseases
Possession of an innate resistance to Dutch elm disease was suggested after inoculation with the causal fungus at the NDSU, however replication of the tests is considered too limited to be conclusive. No other specific information available, but the species generally is highly susceptible to Elm Yellows; it is also moderately preferred for feeding and reproduction by the adult Elm Leaf Beetle Xanthogaleruca luteola [4], and highly preferred for feeding by the Japanese Beetle Popillia japonica [5] [6] in the United States.
Cultivation
Prairie Expedition has been included in the National Elm Trial coordinated by Colorado State University. The tree is in commerce in the USA, and was introduced to the UK from Canada in 2008, and thence to the Netherlands in 2010.
Etymology
The tree is named for the Lewis & Clark prairie expedition of 1804.