Westerdijk was just thirty-four when she gave her inaugural address in Utrecht. One of the photographs taken on this occasion shows her in a static pose, standing beside a column. She is wearing a black gown and has a book in her left hand. A white jabot dangles below her chin, and her flat black beret is stuck upright on her head. She gazes earnestly into the camera, her eyes hidden as always behind the thick lenses of her glasses. It is a stately portrait, so dark that her face and jabot provide the only highlights. The picture exudes gravity, a consciousness that history was being made.

Her students took a slightly different view. After the ceremony they ascribed the following lines to her in a musical:

‘In my black tent I bring to mind

A laundry basket from ancient times.’

Westerdijk laughed good-humouredly.

Her appearance changed little over the years. Anyone who leafs through a few of the photographs in the International Information Centre and Archives for the Women's Movement will easily pick out the ‘Lady Professor’ even in a large group of people, not only on account of her appearance – an ample figure in a tent dress, thick glasses pinching her nose, heavy chin and plump cheeks, resolute bottom lip – but also because of her position and forceful gaze. If Villa Java was the setting for academic phytopathology, Westerdijk, whether in radiant or earnest mood always a strong presence, was its absolute centre.

She was also a woman in a world that had hitherto been dominated by men. Countless stories highlight this anomaly. At the first professorial social event she attended, Westerdijk was reported to have ostentatiously lit a large cigar, prompting one of her male colleagues to slap her heartily on the back, exclaiming words to the effect of ‘Hallo old chap, how's life?’ In a cigar-less version of this story, Westerdijk was welcomed with the equally absurd ‘How do, old girl!’

Anecdotes frequently cite her booming laugh, her love of parties, drinking and dancing, her distaste for marriage and other pointless conventions, her short-sightedness, and her expressive eyes, whether mocking, interested, or full of sympathy.