More about this story: I just finished a cross-country trip to Philadelphia this month, and found the three-leaf whorled neon stonecrop growing ONLY by the front sidewalk of my parents' house. Their other plantings were opposing two-leaf and alternating leaf versions. My brother also had two-leaf opposing plants at his house.
Meanwhile, our west coast drought seems to be causing weird behavior. All mine are starting to have flower buds early. The Oregon Stonecrop has just flowered.
