  We study the effects of anisotropic order parameters on the temperature
dependence of London penetration depth anisotropy $\gamma_\lambda(T)$. After
MgB$_2$, this dependence is commonly attributed to distinct gaps on multi-band
Fermi surfaces in superconductors. We have found, however, that the anisotropy
parameter may depend on temperature also in one-band materials with anisotropic
order parameters $\Delta(T,k_F)$, a few such examples are given. We have found
also that for different order parameters, the temperature dependence of
$\Delta(T)/\Delta(0)$ can be represented with good accuracy by the
interpolation suggested by D. Einzel, J. Low Temp. Phys, {\bf 131}, 1 (2003),
which simplifies considerably the evaluation of $\gamma_\lambda(T)$. Of
particular interest is mixed order parameters of two symmetries for which
$\gamma_\lambda(T)$ may go through a maximum for a certain relative weight of
two phases. Also, for this case, we find that the ratio $\Delta_{max}(0)/T_c$
may exceed substantially the weak coupling limit of 1.76. It, however, does not
imply a strong coupling, rather it is due to significantly anisotropic angular
variation of $\Delta$.
