When in 2008 the National Herbarium of the Netherlands, Utrecht University branch (NHN-U) was closed, Gea Zijlstra could continue her work for the ING as a honorary staff member at the Laboratory of Palaeobotany and Palynology. At that moment, this group still was part of the faculty of Biology. In 2012, this group moved to the faculty of Geological Sciences, and since then she is among the Marine Palynology section.

Gea started with working for the Index Nominum Genericorum (Plantarum) (ING) in September 1972 at the Institute of Systematic Botany (the predecessor of the NHN-U). Here she originally (along with Dr. J.A. Leussink) belonged to the section of prof. dr. F.A. Stafleu, who in 1954 along with prof. Dr. J. Lanjouw had started th ING project of the International Association for Plant Taxonomy (IAPT).

After having finished her study in biology in April 1968, she started with a plant sociological investigation, half-time from September 1968 – September 1972. Besides this, she had a half-time job as a teacher at a high school in Ede.

Gea did a study in biology from September 1961 until April 1968 at the Utrecht University, main subject plant sociology & plant taxonomy, subsidiary subjects plant physiology and phytopathology.

From September 1960 – September 1961, she worked as a laboratory assistant at the CBS, the Fungal Biodiversity Centre that nowadays is an institute of the Royal Netherlands Academy of Arts and Sciences. Here she had the opportunity to join a phytopathology course for students in biology, and this experience made her conclude ‘I should study biology!’

In 1960, Gea had got a diplom at a secondary school in Hilversum.

Gea was born in a small village in Friesland, this is in the north of The Netherlands; in 1946, the family moved to the province of Utrecht, in the centre of our country.