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Cultivation of Dryandra

Margaret Pieroni and Keith Alcock

Dryandra is a large group of 92 species and 34 infraspecific taxa belonging to the Proteaceae family. Their nearest relatives are the banksias. Both groups have flower heads or inflorescences made up of many hundreds or even thousands of individual flowers. The Banksia flowers are borne on elongated spikes, whereas the Dryandra flower heads are flattened and more like a waratah. Dryandras characteristically have a ring of bracts around the base of the flower heads. While in some species these are inconspicuous once the flowers have opened, a number of species have large showy bracts which surround the flower heads and show them off, much in the same way as the South African proteas. With some exceptions the flowers of dryandras are smaller than banksias, but what they lack in size they make up in numbers, for most species flower in profusion with flower heads sometimes growing at almost every leaf axil.

Flower colour is predominately yellow but every shade of yellow in the spectrum is represented, from greenish and lemon yellow through to rich, egg-yolk yellow and golden orange. Some have the yellow flowers suffused with pink, while there are about half a dozen species with red or wine coloured flowers. The remainder have brown shaded flowers, often two-toned, with colours ranging from chocolate and purplish brown through reddish brown and tan to light yellow brown and buff.

Dryandra proteoides. Select the thumbnail image or highlighted name for a higher resolution image (43k). Photo: Margaret Pieroni

Dryandra quercifolia. Select the thumbnail image or highlighted name for a higher resolution image (41k). Photo: Margaret Pieroni

The bracts of dryandras are a very variable feature. In the 10-12 species with large showy bracts, such as D.proteoides, D.ferruginea and D.quercifolia, they are smooth and shiny and either golden brown or bronze in colour. They frame the yellow flowers to perfection. A few other species, such as D.speciosa, D.shutlleworthiana and D.plumosa have large furry bracts in brown tones, which complement the central flowers. In the remaining species the bracts are smaller, enveloping the flower buds but remaining inconspicuously at the base of the flower heads as they open.

Dryandras are small to medium shrubs which show a tremendous variation in form and foliage. They are probably the most attractive group of foliage plants in the Australian flora. There are about 25 prostrate or dwarf species, and about 20 tall shrubs that consistently reach over 2.5 metres in height. The rest range from 0.5 to 2 metres tall and may be upright or spreading in habit. Leaf form is a particularly attractive feature. Leaves are seldom entire, being frequently prickly toothed, pinnatifid or pinnate, or coarsely segmented. Leaf shape ranges from short linear and medium sized obovate to lanceolate. However, most are linear and usually very long and narrow, setting off the serrations to perfection.

Habitat

All dryandras are confined to the south-west of Western Australia and, while some are limited in occurrence, many are widespread though discontinuous in their distribution. They commonly occur in shallow, poor and clayey soils, most notably in lateritic gravelly situations. Where they occur in sandplain country they are usually indicators of shallow sand over lateritic gravel. While soils are shallow and poor they are invariably well drained.

Dryandras often occur in communities with more than one species present and are the dominant plants in such spots. Only a few species, including D.formosa, D.praemorsa, D.nobilis, D.squarrosa and sometimes D.polycephala and D.hewardiana occur in shade in forested situations. The remainder grow in full sun, though in communities rather than exposed positions.

Cultivation Requirements

The prime requirement for dryandras to grow well in cultivation is a freely drained topsoil While they come from shallow soils in the west and are more adaptable than banksias to shallow clay soils, they thrive on deep sandy soils and deep loams as well as shallow rocky soils - so long as all are well drained. Where soils are not naturally well drained, most dryandras will do well in beds raised 12-20 cm above ground level.

A sunny situation is necessary for most species. Most can tolerate dryness once established. Fertilisers are not usually necessary, though small applications of blood and bone or slow release fertilisers such as low phosphorus Osmocote are helpful at planting time. In alkaline soils some yellowing of leaves may be noted and may require foliar sprays of iron chelates to correct.

Hardy Dryandras for Beginners

The more dryandras are tried in cultivation the longer the list proven to be hardy. However, a number of species have long been in cultivation and are known to perform well under a variety of conditions. These include: D.praemorsa, D.fraseri, D.tenuifolia, D.cuneata, D.nivea, D.nervosa, D.quercifolia, D.drummondii, and D.obtusa.

Dryandra obtusa. Select the thumbnail image or highlighted name for a higher resolution image (35k). Photo: Margaret Pieroni

Dryandra praemorsa var. splendens. Select the thumbnail image or highlighted name for a higher resolution image (42k). Photo: Margaret Pieroni

Propagation

Dryandras can be grown from seed or cuttings. Seed is generally the most reliable, provided simple rules are followed. Most species will need to be extracted from the capsule prior to planting, the exception being the 8 or 9 species which shed seed between seasons or where a seed merchant has extracted seed already. Capsules can be 'popped' by heating in a fry pan at low heat (150-200°C) until they open or, more safely, the edges can be clipped off with nail clippers enabling the two halves to be prised open. Capsules contain one or two seeds either side of a separator.

Extracted seed is sown onto a sandy well drained mix, lightly covered with sand and kept in an open warm and sunny spot. Late February or April-May in Western Australia and South Australia and early September are the best times to sow. Prick out seedlings soon after they emerge (4-6 weeks) and pot on into an open friable mix with coarse sand the dominant component.

More variable results are obtained with cuttings, which have the added disadvantage that growth is often thick and unsuited to conventional treatment. Most success has been with semi-hard side shoot growth taken in late spring and mid-autumn.

The Dryandra Study Group

The Dryandra Study Group of the Society for Growing Australian Plants has been in operation since 1974. The group has established a plantation at the Cranbourne (Victoria) annex of the Melbourne Botanic Gardens where well over 1000 plants are thriving. Most taxa are represented.

The Study Group maintains a seed bank available free to all members and shares field observations and experiences of members with propagation and cultivation through its newsletter. The first ten newsletters have been compiled into a 110 page spirally bound book and is available for sale at $7.00 plus postage, and other back newsletters at $3.00 plus postage, from the Study Group. Annual membership is $6.00.

Dryandra tenuifolia var. tenuifolia. Select the thumbnail image or highlighted name for a higher resolution image (24k). Photo: Margaret Pieroni

Margaret Pieroni is the current leader of ASGAP's Dryandra Study Group and Keith Alcock is a former leader. This article was prepared by Margaret based on an earlier article written by Keith.

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Australian Plants online - September 1999
The Society for Growing Australian Plants