Banksia elegans

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Elegant Banksia
in cultivation, Perth
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
Order: Proteales
Family: Proteaceae
Genus: Banksia
Species: B. elegans
Binomial name
Banksia elegans
Meisn.

Banksia elegans, commonly known as the elegant banksia, is a species of shrub or small tree in the plant genus Banksia. Reaching 4 m (13 ft) high, it is a suckering shrub which rarely reproduces by seed. The round to oval yellow flower spikes appear in spring and summer. It is most closely related to the three species in the subgenus Isostylis. It occurs only over a 65 square kilometre area north and west of Eneabba, Western Australia.

Description

Banksia elegans grows as a many-stemmed spreading shrub to 4 m (13 ft) high. It commonly sends up suckers. The trunk is up to 15 cm (6 in) in diameter and covered with grey tesselated bark, and the new stems are covered with fine hair and become smooth with maturity. The long thin pale blue-green leaves range from 20 to 45 cm long and 1.2-1.8 cm wide. Their margins are prominently serrated in a saw-tooth pattern with triangular teeth and v-shaped sinuses. The yellow flower spikes, or inflorescences, are oval or spherical and reach 6 or 7 cm in diameter.[1] Each flower spike is composed of around 400 individual flowers. Over 90% of plants and 99% of flowerheads do not develop follicles and hence set no seed.[2]

Taxonomy

Swiss botanist Carl Meissner described Banksia elegans in 1855. George was uncertain of its relationships, though noted that the follicles and seed are not unlike those of B. ilicifolia and B. cuneata, and that it clearly had a shortening of its woody axis in the flower spike.[1]

In 2002, a molecular study by Austin Mast showed B. elegans was basal to a group formed by the three members of the subgenus Isostylis, and that its next closest relative was B. attenuata[3]

In 2005, Mast, Eric Jones and Shawn Havery published the results of their cladistic analyses of DNA sequence data for Banksia. They inferred a phylogeny greatly different from the accepted taxonomic arrangement, including finding Banksia to be paraphyletic with respect to Dryandra.[4] A new taxonomic arrangement was not published at the time, but early in 2007 Mast and Thiele initiated a rearrangement by transferring Dryandra to Banksia, and publishing B. subg. Spathulatae for the species having spoon-shaped cotyledons; in this way they also redefined the autonym B. subg. Banksia. They foreshadowed publishing a full arrangement once DNA sampling of Dryandra was complete. In the meantime, if Mast and Thiele's nomenclatural changes are taken as an interim arrangement, then B. elegans is placed in B. subg. Banksia.[5]

Ecology

Banksia elegans sets an extremely low amount of seed, and appears to reproduce predominantly by suckering, despite prolific flowering and low rates of flower and follicle predation. Developing seeds are also often aborted. A population studied in one field study produced an average of only two seeds per plant in sixteen years.[2] Populations begin flowering three years after bushfire, and regenerate after fire from large underground lignotubers as well as sending up suckers. One field study found no seedlings at all post-bushfire, suggesting the shift to vegetative propagation maybe more marked than thought previously.[6]

An assessment of the potential impact of climate change on this species found that its range is unlikely to contract and may actually grow, depending on how effectively it migrates into newly habitable areas.[7]

Cultivation

Seeds do not require any treatment, and take 19 to 48 days to germinate.[8]


References

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  1. ↑ 1.0 1.1 George, Alex S. (1981). "The Genus Banksia L.f. (Proteaceae)". Nuytsia 3 (3): 239–473 [366–67]. ISSN 0085-4417. 
  2. ↑ 2.0 2.1 Lamont, Byron B.; Barrett, Gregory (1988). "Constraints on Seed Production and Storage in a Root-Suckering Banksia". Journal of Ecology 76 (4): 1069–82. JSTOR 2260634. 
  3. ↑ Mast, Austin R.; Givnish, Thomas J. (August 2002). "Historical biogeography and the origin of stomatal distributions in Banksia and Dryandra (Proteaceae) based on their cpDNA phylogeny". American Journal of Botany 89 (8): 1311–1323. doi:10.3732/ajb.89.8.1311. ISSN 0002-9122. PMID 21665734. 
  4. ↑ Mast, Austin R.; Jones, Eric H.; Havery, Shawn P. (2005). "An assessment of old and new DNA sequence evidence for the paraphyly of Banksia with respect to Dryandra (Proteaceae)". Australian Systematic Botany (CSIRO Publishing / Australian Systematic Botany Society) 18 (1): 75–88. doi:10.1071/SB04015. 
  5. ↑ Mast, Austin R.; Thiele, Kevin (2007). "The transfer of Dryandra R.Br. to Banksia L.f. (Proteaceae)". Australian Systematic Botany 20: 63–71. doi:10.1071/SB06016. 
  6. ↑ Lamont, Byron B. (1988). "Sexual Versus Vegetative Reproduction in Banksia elegans". Botanical Gazette 149 (4): 370–75. JSTOR 2995505. 
  7. ↑ 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): 1–16. doi:10.1111/j.1365-2486.2008.01559.x. 
  8. ↑ Sweedman, Luke; Merritt, David (2006). Australian seeds: a guide to their collection, identification and biology. CSIRO Publishing. p. 203. ISBN 0-643-09298-6. 
  • George, Alex S. (1981). "The Genus Banksia L.f. (Proteaceae)". Nuytsia 3 (3): 239–473. 
  • George, Alex (1999). "Banksia". In Wilson, Annette. 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. 

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