Avocado Seedlings Rooting in Glass Jars

Every Hass avocado in the store traces back to one tree, raised from a seed in the 1920s by Rudolph Hass, a mail carrier in Southern California. Growers keep the variety going by grafting, because a tree grown from a pit comes out different from its parent and can take many years to bear fruit. That has never stopped anyone from trying. Three pits balance on toothpicks over jars of water on a greenhouse shelf, each a little further along than the last. An avocado seedling jigsaw puzzle sounds plain until you see the white roots tangling through the water.