Banksia oligantha
Banksia oligantha | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Proteales |
Family: | Proteaceae |
Genus: | Banksia |
Subgenus: | Banksia subg. Isostylis |
Species: | B. oligantha
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Binomial name | |
Banksia oligantha |
Banksia oligantha, commonly known as Wagin banksia, is an
First collected in 1984 near the wheatbelt town of Wagin, Banksia oligantha was officially described in 1987 by Australian botanist Alex George. Several scattered populations survive in fragments of remnant bushland in a region which has been mostly cleared for agriculture. It has been listed as Declared Rare Flora by the Western Australian Government.
Description
Banksia oligantha grows as a single-trunked small tree or as an erect shrub with few main stems.[1] Reports of its maximum height vary from 3 m (9.8 ft)[2] to 5 m (16 ft).[1] When not in flower it is said to look somewhat like Banksia sessilis (Parrot Bush).[3] It has smooth grey bark for the most part, though bark near the base of the trunk may be lightly fissured in older trees.[4] Young stems are covered in hairs, both short and soft, and long and coarse; these are lost with age.[2]
Its leaves are deep green and glossy above, and a pale matte green below. They are roughly oval-shaped, but concave rather than lying flat. There is a sharp point at the tip, and two to four more such points along each margin. They range in length from 1.5 to 3.7 cm (0.59 to 1.46 in), and in width from 0.4 to 2.0 cm (0.16 to 0.79 in), with a petiole 2 to 3 mm (0.079 to 0.118 in) long. Young leaves have a coating of woolly hairs on both sides, but these are soon lost except in pits in the undersurface.[2]
Appearing from October to December (late spring), the flowers occur in dome-shaped
Old flowers soon fall from the flower heads, revealing a woody dome with 1 to 6 follicles embedded in it. These are a mottled grey colour, smooth, and shortly furry. They are oval-shaped, measuring 14 to 19 mm (0.55 to 0.75 in) long by 10 to 15 mm (0.39 to 0.59 in) high by 8 to 9 mm (0.31 to 0.35 in) wide. Each follicle contains up to two winged seeds, from 17 to 20 mm (0.67 to 0.79 in) long.[2][5]
Banksia oligantha is most easily distinguished from the other two species in B. subg. Isostylis by its smaller leaves, flowers and fruit.[2] Its foliage is also not as prickly as that of B. cuneata.[6]
Taxonomy
Discovery and naming
Banksia oligantha was discovered by Ken Wallace of the
The species has an uneventful nomenclatural history: it has no synonyms, and no subspecies or varieties have been published.[8]
Infrageneric placement
George placed B. oligantha in subgenus
- Banksia
- B. subg. Banksia (3 sections, 11 series, 73 species, 11 subspecies, 14 varieties)
- B. subg. Isostylis
- B. ilicifolia
- B. oligantha
- B. cuneata
Since 1998, American botanist
Early in 2007, Mast and Thiele rearranged the genus Banksia by merging Dryandra into it, and publishing B. subg. Spathulatae for the taxa having spoon-shaped cotyledons; thus B. subg. Banksia was redefined as encompassing taxa lacking spoon-shaped cotyledons. 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. oligantha is placed in B. subg. Banksia.[13]
Phylogeny
Relationships between B. oligantha and the other members of B. subg. Isostylis still remain unclear. Though Mast's studies found B. cuneata to be the most basal of the three species,
Distribution and habitat
Banksia oligantha occurs over a range of about 100 kilometres (62 miles) in southern parts of the
- The first known population, at Wangelling Gully Nature Reserve in Tarwonga. This population appears to be in decline: in 1988 it was estimated as containing from 500 to 800 plants, but a 2001 survey found only 198 adults, 1 seedling, and 286 dead plants; and a 2004 survey found 135 adults, no seedlings, and 174 dead plants.[1]
- A healthy population at Katanning, spanning two Native Settlement reserves and some private property. This population appears to be increasing; a 2004 survey found nearly 1400 adult plants and over 500 seedlings.[1]
- A small population at Dudinin, spanning a nature reserve and private property. This population is apparently in decline. No seedlings have ever been reported at this location, and from 1997 to 2004 the number of reported adults fell from around 110 to 13.[1]
- A recently discovered healthy population on private property at Toolibin. A 2004 survey counted 188 adults, 35 seedlings, and 36 dead plants.[1]
The species grows in sand dunes of white,[2] white-grey[1] or yellow-brown sand, amongst a system of ephemeral salt creeks.[15] Populations occur both in low-lying areas near creeks, and atop dunes.[1] The vegetation has been described as low open woodland over heath,[1] and as tall open shrubland[2] with some scattered trees.[15]
Ecology
Little has been published on the ecology of B. oligantha. Its lifespan is probably around 10 to 30 years.[1]
Six species of
Assessments of the
Like many plants in
Seed germination rates are quite high. One study found germination rates better than 77% in most batches tested. Seed is likely to remain viable for a long time, as seed of the closely related B. cuneata remains viable for around ten years.[1]
Conservation
Banksia oligantha is listed as an endangered species under the federal
Cultivation
Banksia oligantha is rarely seen in cultivation, though it is said to merit more consideration than it receives. It is a fast-growing plant that flowers prolifically, producing "lovely masses of matchstick-like cream flowers". However, its prickly foliage makes it unsuitable for growth near paths, it is prone to lose branches in strong wind, and it is often attacked by woodboring beetles.[5]
Propagation is by seed, but these are hard to obtain.[5] Seeds do not require any treatment before sowing, and take 37 to 40 days to germinate.[19] Propagation by cutting has not been attempted, but might be possible, since the closely related B. cuneata has been propagated this way, albeit with unpredictable results. The plant should be grown in deep, acidic to neutral sand at a sheltered site. It is recommended to prune it when young, to encourage branching.[5]
References
- ^ a b c d e f g h i j k l m n o p Department of Environment and Conservation (2008). "Wagin banksia (Banksia oligantha) Recovery Plan". Interim Recovery Plan No. 220. Retrieved 20 January 2010.
{{cite journal}}
: Cite journal requires|journal=
(help) - ^ ISBN 0-643-06454-0.
- ^ a b c Brown, Andrew (2006). "Endangered: Wagin Banksia". Landscope. 22 (1): 18.
- ^ ISBN 0-86417-006-8.
- ^ ISBN 978-1-876473-68-6.
- ISSN 1444-285X.
- ^ a b c George, Alex (1988). "New taxa and notes on Banksia L.f. (Proteaceae)". Nuytsia. 6 (3): 309–317.
- ^ "Banksia oligantha A.S.George". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- .
- doi:10.1071/SB97026.
- ^ PMID 21665734.
- doi:10.1071/SB04015.
- doi:10.1071/SB06016.
- S2CID 39559876.
- ^ ISBN 0-644-07124-9.
- ^ doi:10.1071/BT06142.
- ^ Banksia oligantha — Wagin Banksia, Species Profile and Threats Database, Department of the Environment and Heritage, Australia.
- Department of Biodiversity, Conservation and Attractions.
- ISBN 0-643-09298-6.
External links
- "Banksia oligantha A.S.George". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
- "Banksia oligantha A.S.George". Department of Biodiversity, Conservation and Attractions.
- Banksia oligantha — Wagin Banksia, Species Profile and Threats Database, Department of the Environment and Heritage, Australia.