関連ワード:  what is the role of a vein in a leaf    what is the function of a vein in a leaf    what is the function of veins in a leaf for class 4    what is the function of veins in a leaf for class 3    what is the purpose of veins in a leaf    what is the function of veins in a leaf class 6    what is the importance of veins in a leaf    what is the function of a vein in a plant    what is the function of side veins in a leaf    what is the main function of veins in a leaf