Thanks for Walter Robertson and Maik for very useful suggestions.
I am now using a slightly simplier approach, as illustrated by the following example;
hQ = quiverm(lat,lon,dlat,dlon);
delete(hQ(1)); % removes arrow line
delete(hQ(2)); % removes arrowhead
Best,
Mark
p.s. Matlab: PLEASE add this information to the description of the quiverm function.