Bhṛgu–Bharadvāja-saṃvāda: Vānaprastha-parivrājaka-ācāra, Abhaya-dharma, and Lokānāṃ Vibhāga (Śānti-parva 185)
पुण्यापुण्यैस्तथा गन्धैर्धूपैश्व विविधैरपि । अरोगाः: पुष्पिता: सन्ति तस्माज्जिप्रन्ति पादपा:,पवित्र और अपवित्र गन्धसे तथा नाना प्रकारके धूपोंकी गन्धसे वृक्ष नीरोग होकर फूलने-फलने लग जाते हैं; इससे प्रमाणित होता है कि वृक्ष भी सूँघते हैं
puṇyāpuṇyais tathā gandhair dhūpaiś ca vividhair api | arogāḥ puṣpitāḥ santi tasmāj jighranti pādapāḥ ||
Bharadvāja said: “By fragrances that are deemed pure and impure, and by many kinds of incense-smoke as well, trees become free from disease and come into blossom and fruit. From this it is established that trees, too, possess the faculty of smelling.”
भरद्वाज उवाच
The verse argues by observable effect (health and blossoming due to fragrances and incense) that trees possess a sensory capacity—specifically smell—thus extending consideration of sentience beyond humans and animals.
In a didactic discussion in Śānti Parva, Bharadvāja presents an inference: since trees respond beneficially to scents and fumigation, it is reasonable to conclude that they can smell.