IMHO

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Note added at 17 mins (2017-03-10 17:01:19 GMT)
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The Goals of the Demonstration Garden
Demonstrate various types of locally suitable trees, shrubs, and other plants and their uses in home landscapes and gardens.
Raise public awareness of sound gardening practices through teaching, testing and demonstration.
Provide a place of beauty and tranquility for garden visitors of all ages.
http://extension.wsu.edu/benton-franklin/gardening/mastergar...
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Welcome to the
Sherwood Demonstration Garden!

As Master Gardeners, we are committed to educating the general public on sustainable horticulture and pest management practices based on traditional, current, and evolving research. It is our goal that the Sherwood Demonstration Garden will provide the public with a hands-on, interactive experience about research-based, sustainable gardening practices specific to the west slope of El Dorado County, appropriate for all ages and cultures, and reflective of a variety of environments and gardening experiences.
http://mgeldorado.ucanr.edu/Demonstration_Garden/
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Demonstration Gardens
The Penn State Extension Demonstration Gardens are located in North and South Parks. Both parks were established in the spring of 1927, with North Park being the largest park in Allegheny County covering 3,075 acres and South Park 2150 acres.
Demonstration Gardens
The primary purpose of the gardens is to showcase flowering plants that perform well in our climate and soils with minimal maintenance. The gardens include annual display beds of over 125 varieties of annuals. At the end of each season, the plants are evaluated based on their performance in the garden (see links below).http://extension.psu.edu/plants/master-gardener/counties/all...

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Рискну предположить, что здесь «показательный» = «образцово-показательный».