the weierstrass p-function plays a great role in the classic theory of complex elliptic curves. a related function, the weierstrass zeta-function, is used by guerzhoy to construct preimages under the xi-operator of newforms of weight 2, corresponding to elliptic curves.  in this talk, i will discuss a generalization of the weierstrass zeta-function and an application to harmonic maass forms. more precisely, i will describe a construction of a preimage of the xi-operator of a newform of weight k for k>2. this is based on joint work with c. alfes-neumann, j. funke and m. mertens.