An undirected light source like a tree would also be terrible for light pollution. Even if you used conifers to keep them going year-round, they don't seem like

An undirected light source like a tree would also be terrible for light pollution. Even if you used conifers to keep them going year-round, they don't seem like very good street lights. I want a few to use as nightlights. Even if the first plants are fairly dim, if there's not a lot of competing light they could be reasonably effective.