In Marquand Park the canopy is so old and so tall that the light comes down in pieces, and half of Princeton's lawns live under some version of that shade. ADP Land Design and Tree Service reads a yard by the light it gets: what will hold under a beech, where the grass thins in August, which corner needs a longer blade and a lighter hand. On a late-summer afternoon the mowers finish and the stripes lie cool and even beneath the branches. Mowing, trimming, edging and the seasonal cleanups keep a shaded lawn from surrendering to moss and leaf litter. The map runs out from Princeton into Lawrenceville, Kingston, Hopewell and Pennington.