1, the rooting depth of a wheat is generally about 2 meters, and the deepest part can reach 4 meters. The roots of watermelon and pumpkin are 5 meters away from the main stem. 2. A rye has 6.5438+0.4 million small roots with a length of 623.27 kilometers. Spatholobus suberectus is the longest plant in the world, which can reach 300-400 meters. The thickest tree in the world is a chestnut tree called "White Horse Tree", with a circumference of 55 meters. 5. A giant Chinese fir in America, with a height of142m, a diameter of12m and a trunk circumference of 37m.