  We study experimentally and discuss quantitatively the contact angle
hysteresis on striped superhydrophobic surfaces as a function of a solid
fraction, $\phi_S$. It is shown that the receding regime is determined by a
longitudinal sliding motion the deformed contact line. Despite an anisotropy of
the texture the receding contact angle remains isotropic, i.e. is practically
the same in the longitudinal and transverse directions. The cosine of the
receding angle grows nonlinearly with $\phi_S$, in contrast to predictions of
the Cassie equation. To interpret this we develop a simple theoretical model,
which shows that the value of the receding angle depends both on weak defects
at smooth solid areas and on the elastic energy of strong defects at the
borders of stripes, which scales as $\phi_S^2 \ln \phi_S$. The advancing
contact angle was found to be anisotropic, except as in a dilute regime, and
its value is determined by the rolling motion of the drop. The cosine of the
longitudinal advancing angle depends linearly on $\phi_S$, but a satisfactory
fit to the data can only be provided if we generalize the Cassie equation to
account for weak defects. The cosine of the transverse advancing angle is much
smaller and is maximized at $\phi_S\simeq 0.5$. An explanation of its value can
be obtained if we invoke an additional energy due to strong defects in this
direction, which is shown to be proportional to $\phi_S^2$. Finally, the
contact angle hysteresis is found to be quite large and generally anisotropic,
but it becomes isotropic when $\phi_S\leq 0.2$.
