Make legend circles/squares instead of lines

I Have the following code, which produces the attached image. What I would like to do is have the lines in the legend as squares or circles, so they match the image better.

figure(6)
imagesc(lut)
title('Highest Weighted Predictor variable for each Pixel')
ylabel('Longitude')
xlabel('Latitude')
caxis([0, 7])
myColorMap = jet(6);

imagesc(lut, 'AlphaData', ~isnan(lut))
colormap(myColorMap);
L = line(ones(6), ones(6));
set(L, {'Color'}, num2cell(myColorMap, 2))
legend(L, {'Forest','Shrubland','Savanna','Grassland','Agricultural','Barron'})
grid on
ax = gca
ax.GridAlpha = .2
ax.XTick = [5 10 15 20 25 30 35 40];
ax.YTick = [5 10 15 20 25 30];
ax.XTickLabel = {'118^{o}E','123^{o}E','128^{o}E', '133^{o}E', '138^{o}E', '143^{o}E','148^{o}E', '153^{o}E'};
ax.YTickLabel = {'13^{o}S','18^{o}S','23^{o}S','28^{o}S','33^{o}S','38^{o}S'};
ax.TickLength =[0.0 0.0]

Answer 1

[KSSV]

You may read this:

http://in.mathworks.com/matlabcentral/answers/711-combining-legend-data http://in.mathworks.com/matlabcentral/answers/711-combining-legend-data