In the erect position of the leaf the lower side has its cells extremely turgid, and the pulvinus thus forms a cushion, holding up the petiole.
20, p), forming the pulvinus, formed of cellular tissue, the cells of which exhibit the phenomenon of irritability.
20) a sensitiveness is located in the pulvinus which upon irritation induces a depression of the whole bipinnate leaf, a similar property exists in the pulvini at the base of the leaflets which fold upwards.
These symbols were laid upon a couch (lectus), the left arm resting on a cushion (pulvinus, whence the couch itself was often called pulvinar) in the attitude of reclining.
Irritability resides in the pulvinus,in the pea and bean family, in rosaceous plants and the family Rubiaceae.