Sandro (Alessandro) Pignatti (born 1930) is an Italian botanist specialising in pteridophytes and spermatophytes. The Australian plant species, Calectasia pignattiana was named after him. "The specific epithet honours Professors Erika and Alessandro Pignatti of Rome on the occasion of their seventieth birthdays. They have contributed greatly to our knowledge of south-west vegetation associations and have collected extensively, including many taxa new to science."