Final answer:
The author develops the idea that Washington's cherry trees have been expertly cared for by providing examples of how closely they are planted, the knowledge of the gardeners about the different types of cherry trees, and the thriving condition of the trees.
Step-by-step explanation:
The author develops the idea that Washington's cherry trees have been expertly cared for through the following:
By stating that the trees are planted as closely as currant bushes, the author highlights how many trees the city is able to accommodate.
By stating that the Tamagukura is the first to bloom, the tallest, and the longest-lived, the author highlights the gardeners' knowledge of the various types of cherry trees.
By stating that the trees reach around both waterfronts and into the streets, the author highlights that the cherry trees are thriving.
These examples demonstrate the meticulous care and attention given to the cherry trees in Washington.