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Developing Australian Plants for Commercial Horticulture

Peter Ollerenshaw


When my wife and I established Bywong Nursery and offered tube stock to growers we discovered one of their first questions was "what have you got that is new?" The development work that is described in this article is essentially our response to that question.

Work on Leptospermum

Leptospermum spectabile  
Leptospermum spectabile
Click for larger image

On a visit to New Zealand in 1980 I saw the results of some Leptospermum hybridisation. As New Zealand has only one Leptospermum species and Australia has 86, I thought there might be an opportunity for experimentation and to develop something "new"! In the genus Leptospermum we have great variation. They range from trees to groundcovers and grow from tropical to alpine climates. Some grow in waterlogged sites of swamps and riverbanks and others on well-drained ridge tops or sand dunes. Flower colour is mostly white but mauve and pink forms occur and there is at least one red flowering species (Leptospermum spectabile). Flowering time is also quite prolonged. In our area (Bungendore, New South Wales), flowering commences about October and it is possible to find a succession of species flowering until March/April.

As Leptospermum is easy to grow from both seed and cuttings and there is such a wide genetic base available, it seemed that it should be possible to develop a whole new range of Leptospermum cultivars based on Australian species.

One of the first species we wanted in our breeding program was Leptospermum spectabile. We grew a batch from seed and by chance found a few seedlings that were unlike the rest. I saved these and grew them on and eventually named one Leptospermum 'Aphrodite'.

Leptospermum rotundifolium  
Leptospermum rotundifolium
Click for larger image

Another species I thought had potential was Leptospermum rotundifolium. I crossed it with L.spectabile and raised a number of seedlings. From these I selected one and named it Leptospermum 'Rhiannon'. I then made quite a few Leptospermum crosses and planted them out at our nursery. While they were all different and attractive (at least to me) only a few have been selected for marketing. I was initially looking for hardy plants in new colours to suit most gardens. However, over time our growers recommended a more important characteristic. They felt that new varieties should also be capable of flowering the first season in a 140mm pot. This was because these days, plants mostly only sell when they are in flower. Only a few of our native tea trees are capable of this and most of our early crosses did not have this character.

Intellectual property

  Leptospermum 'Aphrodite'
  Leptospermum 'Rhiannon'
  Leptospermum 'Aphrodite' (top)
Leptospermum 'Rhiannon' (bottom)
Photos: Peter Ollerenshaw
Click for larger image

As Leptospermum 'Aphrodite' was quite different from other leptospermums, I thought it might be possible to gain Plant Breeders Rights (PBR) registration. After finding someone to act as my "Qualified Person" to oversee my application, I applied for PBR, set up a comparison trial with the closest known varieties and after careful measuring, etc, eventually gained the rights to Leptospermum 'Aphrodite'. Subsequently we have been granted PBR on the other eight cultivars we have submitted.

What gaining PBR has done is to allow us to develop the finished product, although we are only involved in the development and propagation stages.

Because we own the rights to our plants we can stipulate to growers how we wish to see our products presented to the market. We became aware of this after 'Aphrodite' was found to be difficult to flower in a 140mm pot. In order to sell plants we had to dress them up so that they looked attractive without flowers. So now we generally have a package to offer growers on all new cultivars. It includes the label, the pot and the advertising and some fact sheets and advice on growing and presentation. We have contracts with all our growers and these points are stipulated in it.

Method of Leptospermum hybridisation

  Leptospermum 'Outrageous'
  Leptospermum 'Tickled Pink'
  Leptospermum 'Outrageous' (top)
Leptospermum 'Tickled Pink' (bottom)
Photos: Peter Ollerenshaw
Click for larger image

I select a small branch that has about five or six flower buds that are about to open. I remove all open flowers and all buds that are not developed enough. I then carefully remove sepals, petals and stamen on the remaining flowers. These flowers are then covered with a plastic bag to prevent visitation by pollen carrying insects. After three or four days the bags are removed and the flower stigma dusted with the required pollen. The flowers are then tagged and all information about the cross noted in my field book. The flowers are covered with the bags again and left for about two weeks for pollination to take place. After that the bags are removed and the seedpods are given about six months to mature. Seedpods can be picked, dried and sown in the normal method. However it is essential that the cross can be easily identified at all times. Seedlings are planted out and regularly monitored. Plants that are promising are propagated and assessed in pots before a decision on marketability is made.

Other genera

When you start breeding plants and have seen the results of some crosses you look at all plants with new eyes. Suddenly you start thinking about combinations of characters that might be possible.

With this in mind I started trying to breed new Correa, Crowea and Prostanthera. The idea seemed good but the results were very disappointing and they have been put aside for a while. Undaunted, I have moved on to other genera and now have had some success with Grevillea, Pelargonium and Bracteantha (now Xerochrysum...ed).

Two of our newly developed grevillea have now been released to the market. They are:

  • Grevillea 'Ember Glow' - a cross between Grevillea rhyolitica and Grevillea juniperina (prostrate red)
  • Grevillea 'Bedspread' - a cross between Grevillea wilkinsonii and Grevillea 'Poorinda Royal Mantle'.
Grevillea 'Bedspread' Grevillea 'Bedspread'
Grevillea 'Bedspread' (left); Grevillea 'Ember Glow" (right)
Photos: Peter Ollerenshaw

The future

In my opinion, there will always be a place in the garden for natural species of Australian plants. However, the potential to breed and develop new cultivars is enormous.

With the large modern house and tiny garden, the demand is for smaller and smaller plants that flower prolifically and require very little maintenance. With careful selection of species, it should be possible to develop an exciting range of plants to suit new native gardeners who we are told are time poor and space challenged.

This article was originally presented at the ASGAP 21st Biennial Seminar which was held in Canberra, ACT, 1 to 5 October 2001.

Peter and his wife Jennifer are the owners of Bywong Nursery situated 25k north east of Canberra. They specialise in the propagation of a wide range of Australian and exotic plants. During the past twelve years Peter has spent a great deal of time developing new Australian plants. Before establishing Bywong Nursery, Peter worked at the Australian National Botanic Gardens for twenty years.


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Australian Plants online - December 2002
Association of Societies for Growing Australian Plants