The identity of Micranthu serpyllifolius Roth

Recently I got the opportunity of examining a specimen from the “Rijksherbarium”, Leiden, which was provided with a label on which ROTH had written in the middle the name of the plant, viz. “ Micranthus serpyllifol-Roth ” and in the lower right corner the name of the collector, viz. “Heyne”; in the lower left comer another hand had added “Ind. or. Hb. Roth”. As the specimen proved to answer the description of Micranthus serpyllifolius given on p. 282 of ROTH’s “Novae Plantarum Species, Halberstadt 1821,” there can be little doubt that it is either the type of this species or else a duplicate of the latter. This is the more important as none of the authors who in the past ventured an opinion with regard to the taxonomic position of ROTH’s species, apparently had seen the type. ROTH’s specimen was inserted in the Leiden Herbarium under the name Andrographis serpyllifolia R.W. (Acanthaceae), but this is obviously a misidentification. for Andrographis serpyllifolia does not fit ROTH’s description. The plant described by the latter has smaller and less numerous leaves and its flowers are arranged in terminal spikes instead of solitary or a few together in the axils of ordinary leaves.