The kitchen windowsill holds several treasures I’ve collected over time. One, a birthday gift from my Aunt Ann, is a small white vase etched with a garden scene. Usually a pink camellia or a few pansies fill the vase, but today it’s home to my Swedish ivy. This isn’t just any Swedish ivy, by the way. The plant from which this cutting grew graces the mantle of the White House Oval Office. So how did someone without a green thumb acquire this distinguished ivy? My son, Corban, received a cutting from a work colleague, and Corban’s talented mother-in-law, who does have a green thumb, rooted the ivy and gave everyone…