Banksia leptophylla
Encyclopedia
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.
, 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". It was first noted by Byron Lamont in 1980; he attributed it to cyanobacteria that feed off the nectar sugar
s. Noting that many of these cyanobacteria had heterocyst
s, 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.
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Banksia
Banksia
Banksia is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes and fruiting "cones" and heads. When it comes to size, banksias range from prostrate woody shrubs to trees up...
. It occurs along the west coast of Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
from Gingin
Gingin, Western Australia
Gingin is an agricultural town in Western Australia. The town is located north of Perth along the Brand Highway.The town is well suited for agriculture with a mild climate and available water sources...
to Kalbarri
Kalbarri, Western Australia
Kalbarri is a coastal town in the Mid West region located 592 km north of Perth, Western Australia. The town is found at the mouth of the Murchison River and has an elevation of...
. Before Alex George's revision of 1981, it was labelled informally as B. sphaerocarpa var. pinifolia or var. major.
Ecology
B. leptophylla is one of five Banksia species, all closely related to B. sphaerocarpaBanksia sphaerocarpa
Banksia sphaerocarpa, commonly known as the Fox Banksia or Round-fruit Banksia, is a species of shrub or tree in the plant genus Banksia . It is generally encountered as a 1–2 m high shrub, and is usually smaller in the north of its range...
, 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". It was first noted by Byron Lamont in 1980; he attributed it to cyanobacteria that feed off the nectar sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s. Noting that many of these cyanobacteria had heterocyst
Heterocyst
Heterocysts are specialized nitrogen-fixing cells formed by some filamentous cyanobacteria, such as Nostoc punctiforme, Cylindrospermum stagnale and Anabaena sphaerica, during nitrogen starvation. They fix nitrogen from dinitrogen in the air using the enzyme nitrogenase, in order to provide the...
s, he speculated that they aid the plant by fixing atmospheric nitrogen
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...
, which is then washed off the flower heads by rain, and absorbed by the proteoid root mat. This purported symbiosis
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
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
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
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.