定义：a small cluster of elongated flexible outgrowths attached or close together at the base and free at the opposite ends especially; a growing bunch of grasses or close-set plants"
定义：a plant that produces wood as its structural tissue. Wood is a structural cellular adaptation that allows woody plants to grow from above ground stems year after year, thus making some woody plants the largest and tallest terrestrial plants. Wood is usually primarily composed of xylem cells with cell walls made of cellulose and lignin
