The origin story of Mrs. Robb's Bonnet is one of botany's more charming footnotes. Mary Ann Robb encountered this plant near Istanbul in 1891 and transported seeds and cuttings back to her home in Hampshire, England, using her hatbox as a makeshift plant carrier — an act of horticultural improvisation that gave the plant its enduring common name. The subspecies robbiae differs from the broader Euphorbia amygdaloides species in its broader, darker leaves and more aggressive rhizomatous spread, which makes it a formidable ground cover where lesser plants give up.

In the garden, this evergreen perennial earns its keep in shade and dry conditions that challenge most plants. Growing 1 to 2 feet tall, it forms dense carpets of shiny, deep green rosettes topped in spring with lime-green bracts that glow against dark foliage. It tolerates poor, rocky, or sandy soils and manages perfectly well in dry shade, though it rewards occasional moisture with a fuller habit. The rhizomatous spread is vigorous, so site it where the expansion can be appreciated rather than constrained. As with all euphorbias, the milky sap demands gloves, and all parts are toxic if ingested.