Verse 55

सहस्राङ्कुरशाखात्मफलपल्लवशालिनः ।अस्य संसारवृक्षस्य मनो मूलमहाङ्कुरः

In plain words

Of this tree of saṃsāra, rich with a thousand sprouts, branches, its own fruit and shoots, the mind is the root, the great first sprout.