Lawson was interested in succulent plants and was encouraged by Archdeacon Frederick A. Rogers to collect specimens. Lawson prepared herbarium specimens and presented plants for identification to Maria Wilman, who was then director of the McGregor Museum in Kimberley. Wilman passed some of Lawson's specimens on to the Bolus Herbarium in Cape Town. The species Ruschia lawsonii (Perdevygie) was named after him by Louisa Bolus.
