The Slender-leaved banksia (Banksia leptophylla) is a species of shrub in the plant genus Banksia. It occurs along the west coast of Western Australia from Gingin to Kalbarri. Before Alex George's revision of 1981, it was labelled informally as B. sphaerocarpa var. pinifolia or var. major.
B. leptophylla is one of five Banksia species, all closely related to B. sphaerocarpa, that have highly unusual flower nectar.[a] 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, and eventually becoming "an almost black, gelatinous lump adhering to the base of the flowers". It was first noted by Byron Lamont in 1980; he attributed it to cyanobacteria that feed 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 by Barrett and Lamont in 1985, but no evidence of nitrogen fixing was found. Further investigation by Markey and Lamont 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". Their analyses indicated that the nectar had unusually high levels of sugar and free amino acids, but three of these species, including B. leptophylla, have since been shown to have normal nectar sugar compositions.
An assessment of the potential impact of climate change on B. leptophylla found that its range is unlikely to contract and may actually grow, depending on the severity of the change and how effectively the species migrates into newly habitable areas.
- Blake, T. (1982). "The Banksia Revision". Banksia Study Report. Ringwood, Victoria: Banksia Study Group (6): 1–19. ISSN 0728-2893.
- Hansen, Dennis M.; Olesen, Jens M.; Mione, Thomas; Johnson, Steven D.; Müller, Christine B. (2007). "Coloured Nectar: Distribution, Ecology, and Evolution of an Enigmatic Floral Trait" (PDF). Biological Reviews. 82 (1): 83–111. doi:10.1111/j.1469-185X.2006.00005.x. ISSN 1469-185X. PMID 17313525.
- Lamont, Byron B. (1980). "Blue-green algae in nectar of Banksia aff. Sphaerocarpa". West Australian Naturalist. 14 (7): 193–194.
- Barrett, Gregory J.; Lamont, Byron B. (1985). "Absence of nitrogen fixation (acetylene reduction) by procaryotes in nectar of Banksias". Plant and Soil. 85 (3): 443–445. doi:10.1007/BF02220200.
- Markey, Adrienne S.; Lamont, Byron B. (1996). "Why do some banksias have green nectar?". International Symposium on the Biology of Proteaceae. Royal Botanic Gardens, Melbourne. (only abstract sighted)
- Nicolson, Susan W.; Van Wyk, Ben-Erik (1998). "Nectar sugars in Proteaceae: Patterns and processes". Australian Journal of Botany. 46 (4): 489–504. doi:10.1071/BT97039.
- Fitzpatrick, Matthew C.; Gove, Aaron D.; Sanders, Nathan J.; Dunn, Robert R. (2008). "Climate change, plant migration, and range collapse in a global biodiversity hotspot: the Banksia (Proteaceae) of Western Australia". Global Change Biology. 14 (6): 1337–52. doi:10.1111/j.1365-2486.2008.01559.x.
- George, Alex S. (1981). "The Genus Banksia L.f. (Proteaceae)". Nuytsia. 3 (3): 239–473.
- George, Alex (1999). "Banksia". In Wilson, Annette (ed.). Flora of Australia: Volume 17B: Proteaceae 3: Hakea to Dryandra. CSIRO Publishing / Australian Biological Resources Study. pp. 175–251. ISBN 0-643-06454-0.
- Taylor, Anne; Hopper, Stephen (1988). The Banksia Atlas (Australian Flora and Fauna Series Number 8). Canberra: Australian Government Publishing Service. ISBN 0-644-07124-9.