箭头和散点图的图例？

Question

plt.scatter(tower_height, wat_temp, marker = 's', color = "red",  label = "water temperature")
plt.scatter(tower_height, wet_bulb, marker = 'o', color = 'blue',  label = "wet bulb temperature")
plt.arrow(0.9,28.5, 0,-12.1, label = 'R', width = 0.01, head_width = 0.09)
plt.arrow(0.9,0, 0, 15.6, width = 0.01, head_width = 0.09)
plt.xlabel('tower height(m)')
plt.ylabel('temperature')
plt.legend()

它显示了散点图的图例。有没有办法同时显示箭头和散点图的图例？