Protoplasts have been obtained from protonemata of the moss Physcomitrella patens. By treating these with detergent in a microtubule-stabilising buffer, microtubules can be stained with affinity-purified rabbit anti-bovine tubulin antibodies and then made visible with fluorescein-conjugated goat anti-rabbit serum. Microtubules are seen to form thick, anastomosing networks. This report establishes the feasibility of extending to lower plants, techniques routinely used for animal cells and which are beginning to be used for algal protoplasts and higher plant cells.