SB 10.10.23
sri-suka uvaca
evam uktva sa devarsir
gato narayanasramam
nalakuvara-manigrivav
asatur yamalarjunau
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Sukadeva Gosvami continued: Having thus spoken, the great saint Devarsi Narada returned to his asrama, known as Narayana-asrama, and Nalakuvara and Manigriva became twin arjuna trees.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Arjuna trees are still found in many forests, and their skin is used by cardiologists to prepare medicine for heart trouble. This means that even though they are trees, they are disturbed when skinned for medical science.