This is a continuation of the study of subgroups the Chevalley group 퐺 (Φ,푅) over a ring with a system Φ of roots and a lattice of weights that contain the elementary subgroup 퐸 (Φ,퐾) over a subring of 푅. Recently, Bak and Stepanov considered the case of the symplectic group (i.e., the simply connected group with the system of roots Φ = 퐶 ) in characteristic 2. In the present paper we transfer their result to the case where Φ = 퐵 and to groups with other lattices of weights. As in Nuzhin's paper about the case where is an algebraic extension of a nonperfect field and Φ has multiple connections, the description involves carpet subgroups parametrized by two additive subgroups. In the second part of the paper, the Bruhat decomposition is established for these carpet subgroups and it is shown that they possess a split saturated Tits system. As a corollary, it is proved that they are prime as abstract groups.