CHENNAI: Chennai’s oldest living landmarks, sprawling banyans, towering neem, massive tamarind and even the rare baobab, may soon receive official recognition as “heritage trees”, as a Green Tamil Nadu Mission initiative moves to scientifically document and conserve 50 potential heritage trees across the city.
As per available records, the Adansonia digitata (baobab) is the oldest among them, aged close to 300 years. It is located at Andhra Mahila Sabha on Greenways Road.
“This effort is about formally recognising Chennai’s most ecologically and culturally valuable trees and ensuring they are protected as living heritage,” said I Anwardeen, Principal Chief Conservator of Forests (Research and Education) and Chief Managing Director of the Green Tamil Nadu Mission.
"Many of these trees have stood through generations of the city’s growth and continue to provide critical ecosystem services,” he added.
An interim scientific report submitted by the ICFRE-Institute of Forest Genetics and Tree Breeding (IFGTB), Coimbatore, details how researchers assessed the age and internal health of these trees using a mix of field surveys, historical growth data and advanced non-invasive testing.
The report notes that many of the identified trees are estimated to be more than 100 years old, and several are projected to have crossed 200 years, highlighting their role in Chennai’s urban ecology, microclimate regulation and cultural identity.
The interim findings suggest that several landmark trees could be far older than commonly assumed. For instance, multiple species such as tamarind (Tamarindus indica), jamun (Syzygium cumini), peepal (Ficus religiosa) and illupai (Madhuca longifolia) were estimated to be over 200 years old based on growth-rate projections.
Additional Chief Secretary Supriya Sahu said the heritage-tree initiative is part of a broader push to strengthen Chennai’s urban green cover and link it with the city’s biodiversity index.
“Large old trees are among the most powerful nature-based solutions a city can protect. Recognising them as heritage trees will help ensure long-term care, monitoring and public participation in conservation,” she said.
Officials and researchers said formal notification of heritage trees could also encourage better public awareness and protection, especially at a time when many large avenue trees face damage from unscientific pruning, road widening, root zone compaction and construction activity.
One of the key challenges highlighted is that most species surveyed are “diffuse porous” trees, meaning they do not form clear annual growth rings, making traditional age estimation difficult.
“The absence of distinct annual rings in many tropical species makes age estimation complex, so we triangulate age using growth models, field observations and historical references wherever available,” said C Buvaneswaran, scientist, IFGTB, Coimbatore.
However, the report cautions that these estimates are indicative rather than exact, since growth is shaped by soil conditions, moisture regime, pruning history, pollution stress and the unique growth patterns of open-grown urban trees.
To assess internal tree health and public safety risks, scientists deployed Electrical Resistance Tomography (ERT), a non-destructive technique that maps moisture content and internal wood integrity by measuring resistivity around the trunk.
ERT results helped researchers differentiate between structurally strong heartwood and moisture-rich sapwood, and detect internal anomalies that visual inspection often misses.
“Reliance on external indicators alone can lead to either unnecessary removal of structurally sound trees or retention of internally compromised specimens,” the report notes.
Based on combined Visual Tree Assessment (VTA) and ERT scans, many trees were found suitable for heritage classification, while some were listed as “conditionally suitable”, requiring closer monitoring, targeted coring or risk mitigation. A smaller number were flagged as not suitable for unconditional inclusion due to compromised internal architecture.
Researchers will also study 20 more potential heritage trees next week, as the city-wide mapping and scientific verification exercise continues.
Top 10 oldest heritage trees in Chennai (by age)
Tree species — Predicted age (years) — Location
Adansonia digitata (Baobab) — 239–292 — Andhra Mahila Sabha, Greenways Road, Raja Annamalaipuram
Terminalia arjuna — 203–248 — Railway station, Villivakkam
Hura crepitans — 189–232 — Raja Muthiah Research Library, Taramani
Ficus racemosa — 186–227 — Alli pond, Gandhi Mandapam
Madhuca longifolia — >200 — Guindy National Park
Syzygium cumini — >200 — Guindy National Park
Tamarindus indica — >200 — Kotturpuram
Anogeissus acuminata — >200 — TN Medical Service Corporation, Pantheon Road, Egmore
Schleichera oleosa — >200 — Semmozhi Poonga
Barringtonia acutangula — >200 — Theosophical Society, Adyar