How to give Gray color histogram gray shade instead of blue

Hi, I want the gray shade histogram for grayscale image. here is my code. Can any one help me

% for red color
figure;
imhist(Image_Data(:,:,2));
myHist = findobj(gca, 'Type', 'Stem');
myHist.Color = [0 1 0]
saveas(gcf,'Hist_Org_B.jpg');
%for green color
figure;
imhist(Image_Data(:,:,3));
myHist = findobj(gca, 'Type', 'Stem');
myHist.Color = [0 0 1]
saveas(gcf,'Hist_Org_G.jpg');