Banksia sphaerocarpa

taxobox
name = Fox Banksia

---

image_caption = "B. sphaerocarpa sphaerocarpa"
in gravelpit near Cataby
regnum = Plantae
unranked_divisio = Angiosperms
unranked_classis = Eudicots
ordo = Proteales
familia = Proteaceae
genus = "Banksia"
subgenus = "Banksia" subg. "Banksia"
sectio = "Banksia" sect. "Oncostylis"
series = "Banksia" ser. "Abietinae"
species = "B. sphaerocarpa"
binomial = Banksia sphaerocarpa
binomial_authority = R.Br.|

The Fox Banksia or Round-fruit Banksia ("Banksia sphaerocarpa") is a species of shrub in the plant genus "Banksia". It occurs widely throughout southwest Western Australia, and also extends north along the west coast as far as Geraldton.

Ecology

"B. sphaerocarpa" is one of five closely related "Banksia" species 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, and eventually becoming "an almost black, gelatinous lump adhering to the base of the flowers".cite journal | author = Lamont, Byron B. | year = 1980 | title = Blue-green algae in nectar of Banksia aff. Sphaerocarpa | journal = West Australian Naturalist | volume = 14 | issue = 7 | pages = 193–194] 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.cite journal | author = Barrett, Gregory J. and Byron B. Lamont | year = 1985 | title = Absence of nitrogen fixation (acetylene reduction) by procaryotes in nectar of Banksias | journal = Plant and Soil | volume = 85 | pages = 443–445 | doi = 10.1007/BF02220200] 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,cite conference | first = Adrienne S. | last = Markey | coauthors = Byron B. Lamont | year = 1996 | title = Why do some banksias have green nectar? | booktitle = International Symposium on the Biology of Proteaceae | location = Royal Botanic Gardens, Melbourne (only [https://listserv.heanet.ie/cgi-bin/wa?A2=ind9608&L=algae-l&P=4620 abstract] sighted)] but three of these species, including "B. sphaerocarpa", have since been shown to have normal nectar sugar compositions.cite journal | author = Nicolson, Susan W. and Ben-Erik Van Wyk | year = 1998 | title = Nectar sugars in Proteaceae: Patterns and processes | journal = Australian Journal of Botany | volume = 46 | pages = 489–504 | doi = 10.1071/BT97039]

References

*The genus Banksia L.f. (Proteaceae)
*cite book|author=George, Alex|year=1999|chapter=Banksia|editor=Wilson, Annette (ed.)|title=Flora of Australia: Volume 17B: Proteaceae 3: Hakea to Dryandra|pages=175–251|publisher=CSIRO Publishing / Australian Biological Resources Study|isbn=0-643-06454-0
*The Banksia Atlas

External links

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