<jats:p> Lobelia cardinalis L. was found to contain essentially only one alkaloid, which has been named lobinaline. Its empirical formula probably is C<jats:sub>28</jats:sub>H<jats:sub>38</jats:sub>ON<jats:sub>2</jats:sub>, and this bears no obvious relation to the alkaloids of L. inflata. It does, however, yield benzoic acid on oxidation with alkaline permanganate, but only one mono-substituted benzene nucleus is present. Lobinaline mono-hydrochloride is virtually insoluble in cold water but dissolves readily in dilute acids.