  We characterize nondicrital generalized curve foliations with fixed reduced
separatrix. Moreover, we give suficient conditions when a plane analytic curve
is its reduced separatrix. For that, we introduce a distinguished expression
for a given 1-form, called {\it Weierstrass form}. Then, using Weierstrass
forms, we characterize the nondicritical generalized curve foliations: first,
for foliations with monomial separatrix using toric resolution; second, for
foliations with reduced separatrix, using the $GSV$-index. In this last case
the characterization, which is our main result, could be interpreted in
function of a polar of the foliation and a polar of its reduced separatrix.
