Vaishnava Dharmashastra 46.23

46.23

kuśapalāśodumbarapadmaśaṅkhapuṣpīvaṭabrāhmīsuvarcalāpatraiḥ kvathitasyāmbhasaḥ pratyekaṃ pānena parṇakṛcchraḥ ||

Drinking water boiled with Kusa grass, leaves of the Palâsa and Udumbara trees, of lotuses, of the Sankhapushpî plant, of the banyan tree, and of the Brahmasuvarkalâ plant, each (for one day), is called Parnakrikkhra (leaves penance).