TOM PATTERSON Special Correspondent Changing cultural perceptions of nature over the last two centuries underlie the thought-provoking feature exhibition at Reynolda House this spring. âCross Pollination,â as itâs titled, considers relationships between art and science across this broad historical span. Employing the botanical process of cross-pollination as a metaphor, the exhibit begins with a selection of work by three American virtuoso painters of the 19th century: Thomas Cole (1801-48), Frederic Church (1826-1900) and Martin Johnson Heade (1819-1904). These artists made their reputations by creating vividly detailed landscape paintings and related works that idealized wilderness and the people who lived in its midst. All three are associated with the so-called Hudson River School, a loosely affiliated group of painters named for the river along which several of them lived in upstate New York, an area depicted in many of their paintings.