Dryandra cladistic classification to Banksia - naming dispute

Written by Kevin Collins
Published on Wednesday, 26 February 2014 21:21

 

I, Kevin, a plant enthusiast and banksia educator strongly disagree with the cladistic re-classification of Dryandra, and their absorption into the genus Banksia.  I, along with many others including pre-eminent botanists, researchers and plant enthusiasts, do not accept the new naming and the deletion of the genus Dryandra. This is unprecedented and not warranted. The DNA observations are interesting and noteworthy but serve no useful purpose for plant observation and identity. It is undoubtedly a useful tool for scientists and should remain in that realm.
For identification purpose, the previous taxonomic classification is excellent. Combining the two genera without any consideration of sub-genera, section or series division makes it a daunting and confusing genus, impossible for the non-scientist. The public do not have DNA kits to enable any conclusion on identity.

In my daily operations in talks and with hand out sheets I show the clear differences between Banksia & Dryandra as this is a question often asked.

  • The first and key difference is the seed holding mechanism which is also relevant to other genera of Proteaceae. Pollinated banksia flowers produce a follicle that is imbedded deep into a dense wooden core. These follicles cannot be pulled from the fruiting cone. The sub-section isostylis, are only slightly imbedded, but are still more firmly attached than Dryandra.  Dryandra follicles are attached to a small wooden base by thin “umbilical cords” which can be easily broken by pulling with your fingers to remove them from the seed housing. The housing is not solid wood as in Banksia, but retained dense florets, encapsulated by retained inflorescence bracts.  They are typically in small vase like containers which can be readily cut open with secateurs from the stem side to find the follicles within and simply pulled away from the base. Some have inflorescence bracts totally encapsulating the seed holder whilst others have shorter bracts that don’t cover the follicles. Others have bracts that are insignificant, or fall away, eg. D.sessilis, in which the follicles are more visible, resembling those of the isostylis group of Banksia. The follicles however can still be broken from the base by pulling with your fingers.

  • A second indicator is the retention of inflorescence bracts. The majority of Banksia have no visible or significant bracts whereas Dryandras are visible and often a key component of the housing mechanism.

  • dryandra-fifiloba-inflorescencebanksia-baxtri-fruiting-coneA third clear difference explained is the fire ecology of the two genuses. Banksia fruiting cones are protected from fire by dense floral bracts forming the outer coating of the cone. This is a woolly coating, velvet like, that singes, blackens and goes out in a fire to save the cone. The seeds deeply imbedded within the wooden core are insulated against the severe heat and saved from being cooked. Banksias with exposed follicles (ones with dead florets that fall away) will often open, without fire, however subject to maturity and timing of a fire can open and survive due to the velvet. The species with dead florets retained utilise them to block the sun, and as fuel to generate sufficient heat to split the follicles open during a fire. Dryandras in contrast do not have dense wooden cones with velvety fire resistant bracts. They rely on the retained floral parts for protection. The bushes are denser in habit with foliage closer to the seed containers, which when burnt provides the heat sufficient to pop the top of the follicles open. The retained dense flowers surrounding the follicles are the fire protection as they singe and then stop burning. Different from Banksia florets which burn mostly away generating the extra heat required to open the stronger wooden follicles in the cones.  In fact most dryandra follicles once removed can be snipped on the edges and prized open with fingers to retrieve the seeds. This is not possible with banksia follicles.

  • Another general difference is the nature of the plants.  Dryandra’s rarely exceed 2m shrubs and are predominantly 1m and less with many having underground stems with spreading habit or growing in small mounding clumps. Banksias are, with the exception of a few ground creeping varieties, larger more prominent upright shrubs with some species growing to very large trees, 30m tall and greater than 1m in trunk diameter.

  • A further difference is the number of flowers & shapes of inflorescence (flower head). Banksias typically range from hundreds to thousands in cylindrical, spherical or occasionally domed shaped inflorescences. Dryandras have smaller flower heads with tens to hundreds of flowers in small vase like containers. Straight styled species (thistle like in appearance), looped styled species (Chinese lantern like) with other species having small cylindrical to ovoid shaped flower heads.

Taxonomy still requires visual traits for public identification. The focus of botany needs to remain in easily explained, systematic botany terms with visual traits to maintain public interest. The public interest provides the incentives for funding and preservation of our plants, animals and forests.  Science based taxonomy does not provide the same stimulus and often is employed by multi-national enterprises as a tool to allow exploitation of our dwindling resources. Eg. forests & minerals. This results in loss of natural habitat, although to the contrary, may lead to techniques to save rare plants and animals but is not highly resourced in most instances.
Cladistics identify dryandra as having evolved from banksia. This finding is not in dispute.
Banksias are around 50million years old and dryandra 35 million years.
As dryandra have evolved from banksia with such a huge time span between I believe they should remain a separate entity or genus.
Long may our beloved dryandras live.