In the age when environmental sustainability is among the chief concerns and goals of communities around the world, a number of linguistic studies have been conducted to illuminate the roles of language in protection and destruction of ecological systems. Most of the studies, however, focus on written and/or formal discourses. The present study aims to fill the gap regarding text varieties in ecolinguistic research by exploring informal conversation, focusing on text meanings of lexical items in the semantic domain of environmental issues. The spoken component of the British National Corpus 2014 was employed as data and concordance lines for lexical items tagged as related to environmental issues were extracted and analysed. Drawing on the concept of local textual functions in corpus linguistics (Mahlberg, 2007), the given lexical items were examined in terms of their lexicogrammatical patterns and associated functions before each functional category was interpreted and discussed from an ecolinguistic perspective on the basis of the interrelatedness concept proposed by Goatly (2022). The analysis reveals 10 local textual functions of the given domain of lexical items in British English informal conversation. Through an ecolinguistic lens, these functions suggest that environmental lexis is part of the discursive construction of individuals' social identities and personal stories, reflecting an inseparable relationship between humans and the environment. It is thereby suggested that informal conversational discourse is not less important than other discursive practices in its potential for promoting environmental sustainability.