IT WAS THE GARDENS, predictably, that attracted me when I first visited the Brandywine Conservancy and Museum of Art in Chadds Ford, Pa., some 15 years ago. I was already a convert to the beauty of our native flora, because as a student back in the 1970s, I had worked in the New York Botanical Garden’s native plant collection. That experience also gave me some acquaintance with native-plant cultivation.
However, I had never seen native