She returned to New Zealand in the fifties and wrote the three definitive books on desmid taxonomy.    From Wordnik.com.  [Yatima » 2010 » March] Reference

Closterium - Closterium is a desmid, a microscopic green algae that occurs in all types of freshwater habitats.    From Wordnik.com. Reference

Strikingly symmetrical, each individual desmid is divided into two mirror-image halves, or semicells, which are connected by an isthmus that contains the nucleus.    From Wordnik.com. Reference