Histogram of α-element abundances, [X_α/ H], (top panel) of the samples of stars without planets (green continuous line), stars with small planets (black dashed-triple-dotted line), stars with giant planets (red dashed-dotted line), stars with confirmed BD companions (blue dashed line), and stars with discarded BD candidates, i.e., binaries with low-mass M-dwarf companions (violet dotted line). The left y-axis in the top panel is labeled with the number of stars with and without small and giant planets, whereas the right y-axis shows the number of stars with BD-companion candidates. The lower panel shows cumulative histogram.