Where the Sudbury and the Assabet fold together into the Concord River, the ground lies low and generous — wet meadow, fieldstone wall, white pine shadow leaning across old clapboard streets. Apple Tree Services works that ground as a lawn care and snow removal outfit, laying mowing lines straight down a lawn and cutting the border clean along granite curb and gravel drive, so a yard reads as tended from the road. Come winter the same routes run in the dark, a plow blade peeling a driveway back to bare pavement before the first car near Monument Square turns its engine over. The satisfaction here is plain and physical: an edge that holds, a walk you can cross in shoes, a place that looks looked after in every month it is asked to.