Dryandra - Background

Introduction

Dryandra is a genus of 135 species in the Protea family (Proteaceae) and all occur naturally only in south-western Australia. The genus was created by the botanist Robert Brown based on specimens collected by him at King George Sound in December 1801 and was named in honour of Jonas Dryander, a botanist and librarian. For many years there has been confusion in the taxonomy of Dryandra with many species having no scientific name and others being known by incorrect names. This situation was seemingly resolved in 1996 when the genus was revised by Alex George. More recently, The Dryandra Book (2006) has documented all of George's species as well as additional species described since.

But....

Dryandra or Banksia?

A paper by Mast and Thiele published in February 2007 (see below) proposed that the genus Dryandra be subsumed into Banksia. The paper published new names in Banksia for all (then) currently recognised Dryandra species. This revised classification has been accepted by the Council of Heads of Australasian Herbaria and the new names now appear on Florabase (the website for the Western Australian Herbarium) and in the Australian Plant Census, which is the main online reference for names of Australian native plants.

Mast A R and Thiele K; The transfer of Dryandra R.Br. to Banksia L.f. (Proteaceae); Australian Systematic Botany, 26 February 2007

Despite this, the revised classification has not met with universal approval. Alex George, for example, strongly opposes the change on scientific grounds. The two opposing views are set out in the following articles:

• You don't have to call Dryandra Banksia" by Alex George.
• Why dryandras have changed their name by Kevin Thiele.

The situation is complicated by the fact that there are a number of dryandras that have not yet been formally classified. These will undoubtedly be published, eventually, as Banksia species (i.e. there will probably be no alternative Dryandra names available). In fact, this has already occurred with the recent (2009) publishing of Banksia recurvistylis, a plant closely allied to Dryandra (Banksia) meganotia and which has no name in Dryandra (other than the non-specific Dryandra sp. aff. meganotia).

The differing views on the classification of Dryandra present a problem for ANPSA. Usually we follow the lead of the various Australian herbaria but, in this case, the opposing view cannot be overlooked. At this stage ANPSA is retaining Dryandra as a separate genus but the situation will be kept under review. On the ANPSA website, the revised names in the genus Banksia will also be mentioned alongside the Dryandra names, where appropriate, to minimize confusion.

Characteristics of Dryandra

As might be inferred from the discussion above, Dryandra is closely related to Banksia although the latter genus has a wider distribution and is found in all Australian States and Territories. Irrespective of the final outcome of the botanical classification of Banksia and Dryandra, the latter are quite distinctive horticulturally and no doubt will always be commonly referred to as "dryandras".

	Stages of opening of a Banksia flower (Dryandra is similar)

Like Banksia, the flowers of Dryandra species are quite small but they occur in dense clusters (an inflorescence) which can number several hundred individuals. The sequence of opening of each flower is similar to other members of the Proteaceae and goes through several stages:

1. In bud, each flower appears as an elongated narrow tube (the perianth) comprising four segments each having an anther containing pollen at its tip.
2. As the flower opens, the perianth segments separate to reveal a narrow style. Just before the flower fully opens the anthers transfer their pollen to the tip of the style (the stigma)
3. Finally, the style separates from the perianth. At this stage the style and stigma, with attached pollen, is called a 'pollen presenter' (i.e. it is 'presenting' the pollen to a pollinator, usually a bird or small marsupial, which acts as the agent to transfer pollen from one flower to another for fertilisation.

This sequence is shown in the accompanying diagram (which is based on the opening of a Banksia flower).

In Dryandra, the flowers are arranged in cone-shaped clusters, a feature which differs from the majority of banksias which have the flowers arranged around a vertical axis, giving the familiar cylindrical inflorescence (Banksia subgenus Banksia). The flower spike of Dryandra is superficially similar to the three Banksia species in the sub-genus Isostylis which would not be recognised as banksias by most people. These three species may be an evolutionary link between the two genera.

Family Relationships: Left: Banksia menziesii, a 'typical' Banksia with vertical flower spike (subgenus Banksia). Centre: Banksia cuneata (subgenus Isostylis). Right: Dryandra quercifolia Photos: Jim Barrow, Brian Walters

In Dryandra, the flower heads are surrounded by overlapping, scale-like bracts which often form a conspicuous part of the inflorescence. These bracts are absent in Banksia.

The bracts surrounding the flower heads of Dryandra species may be a conspicuous part of the inflorescence (left - Dryandra ferruginea) or confined to the base of the inflorescence (right - Dryandra formosa). Photos: Margaret Pieroni, Jan Hopgood

The flower clusters of most Dryandra species are cream, yellow, brown or orange in colour. There are one or two species where the inflorescence can have a pink colour in certain forms (eg. D.praemorsa, D.fraseri).

The flowers are followed by more or less woody follicles each containing one or two seeds. Unlike Banksia, where the follicles develop on large cones, the follicles in Dryandra are hidden within the spent flower clusters. In the majority of species these follicles remain tightly closed unless stimulated to open by heat, such as following a bushfire, or on the death of the plant. With a few species, the seed is released annually. The seeds themselves have papery wings which allows them to be distributed by wind.

Most dryandras are small to medium shrubs but there are many which are prostrate with underground stems. At least one species (D.arborea) is of tree proportions. A number of species have a "lignotuber", a woody swelling at or below ground level from which regeneration of the plant can occur if the above ground stems are destroyed.

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