"B. telmatiaea" is one of five "Banksia" species, all closely related to "B. sphaerocarpa", that have highly unusual flower nectar. Whereas other "Banksia" species produce nectar that is clear and watery, the nectar of these species is pale yellow initially, but gradually becomes darker and thicker, changing to a thick, olive-green mucilage within one to two days of secretion. In the case of "B. telmatiaea", it eventually becomes "an almost black, gelatinous lump adhering to the base of the flowers". This unusual nectar was first noted in 1980 by Byron Lamont, who attributed its transformation to the cyanobacteria that he observed feeding off the nectar sugars. Noting that many of these cyanobacteria had heterocysts, he speculated that they aid the plant by fixing atmospheric nitrogen, which is then washed off the flower heads by rain, and absorbed by the proteoid root mat. This purported symbiosis was investigated in 1985, but no evidence of nitrogen fixing was found. Further investigations in 1996 suggested that the discolouration is not caused by cyanobacteria or other microorganisms in the nectar, but is rather "a chemical phenomenon of plant origin". As of February 2007, the cause was still unknown. Chemical analysis of "B. telmatiaea" nectar has shown it to have a normal nectar sugar composition, albeit dominated by sucrose.