They are not closely related to the true primroses (genus "Primula"). The reserve is also home to the rare and tiny purple-flowered Scottish primrose "Primula scotica". Also noticed was profuse flowering of select ornamentals including primula, marigold and stock. Promoting in profuse flowering of select ornamentals including primula, marigold, stock were also noticed. The Scottish Primrose ("Primula scotica"), is endemic to the north coast including Caithness and Orkney. The common name Japanese primrose also applies to the related species "Primula sieboldii". Pin and thrum heterostyly occurs in dimorphic species of "Primula", such as "P. vulgaris". It is closely related to the Arctic species "Primula stricta" and "Primula scandinavica". Both are herbaceous plants with yellow flowers, but "Primula veris" is much smaller. All sections of the genus "Primula" have heterostyle species, altogether 354 species out of 419. John Birch married Primula Clare Haselden in 1960. It was frequently misidentified as or confused with similar species from the genus "Primula". Primula beesiana, now treated as a subspecies of "Primula bulleyana". The meadow is listed as one of the main Primula species meadows in Greater London. Yesnaby is also one of the very few places where Primula scotica grows.