Trifidae are a family of seats comprising three different armchairs which derive from a single typological and formal origin. Small armchair, high backrest armchair and the enclosing lounge chair share a specific tripartite structure, share similar triangulated forms sprouting from a perceived centre resulting in a characteristically floral in character. When chairs are in use, the tilting of their three main structural segments echoes opening and closing of succulent flower petals. This feature, in combination with their explicit trichotomous nature and star-like shape in perspective view, inspired the botanical title of the series. Although the small armchair differs in size and form from the others, while the high and lounge chair share the same base and armrest, all three are observed as neighbouring species in geometric sequences. The backrest variations in two larger models result in their fundamentally different character. Enclosing backrest produces an introverted, exclusive, formally expressive armchair, shielding its user from the immediate context, while the slim, elevated backrest suggests a more sociable, less reserved quality and usage of the chair.