Spectral types and effective temperatures of the donors of CVs (black dots) and LMXB (green triangles) plotted vs. their orbital periods (an update of the Beuermann et al. 1998 list). CVs with remarkably long periods are marked individually. V479 And is shown by a solid blue square. The black dot-dashed line marks the bifurcation period. The red line corresponds to the periods of semi-detached systems with main-sequence donors and 0.7 M_⊙ accretors. The evolutionary track of the system with initial masses of donor and accretor equal to 1 M_⊙ is plotted with the blue line. Dotted parts of the line correspond to a detached state, solid parts of the line to the semi-detached state, while the dash-dotted part corresponds to the semi-detached state in which the mass transfer rate is below 10^-10 M_⊙ yr^-1 and the system may hardly be observed. (i) effective temperatures of CVs below about 4500 K (later than K5) are considered as unreliable and (ii) evolutionary models with gray atmosphere boundary conditions overestimate the T_eff of low-mass stars (Chabrier & Baraffe 1997).