Kangaroo Paws & Relatives – Propagation

Introduction

Propagation of members of the Haemodoraceae is generally by seed or by division of clumps. There is, however, only limited information available on the propagation of some genera.

Because of the popularity of kangaroo paws in cultivation, many cultivars and hybrids have become available. With these, propagation by division of the clumps is preferred to ensure that plants with desirable characteristics of form, flower colour or hardiness are perpetuated (plants propagated from seed may show variations in these characteristics). Commercially, these cultivars and hybrids are often reproduced by tissue culture.

Seed

Seed of many species of Anigozanthos is available from commercial suppliers but seed of other genera is rarely available.

Seed is usually sown without any pre-treatment using conventional seed raising methods. The simplest method is to sow the seed normally in a punnet or pot, cover it lightly and keep moist until germination occurs. This may take a few weeks up to a month or more. Once seedlings have appeared they can be carefully transferred into tubes or small pots in a potting mix designed for Australian native plants.

Another method that has been successful for at least some species is the use of smoke or “smoked water” as a pretreatment. This has been successful in the germination of species of Anigozanthos, Blancoa, Conostylis, Haemodorum and Macropidia and may have practical application for the home propagator. Further information on this procedure is available in the article Smoke Stimulates the Germination of Many Western Australian Plants (see the Further Information tab) and from the Regen 2000 web site.

It should be noted that most hybrids are sterile and do not produce seed.

Division of Clumps

Division is the easiest way of propagating from established plants and is most successful with the more vigorous kangaroo paws such as Anigozanthos flavidus and its hybrids.

Clumps are best divided in autumn but other times are also successful – division in the heat of summer will require adequate protection of the divisions until they have re-established. Clumps can be lifted with a garden fork and, using a tool such as an old bread knife, sections can be from the clump – each section should contain at least three large shoots to give the maximum chance of success. It is advisable to cut all the leaves back by about a third and plant in a well drained potting mix in a suitable container so that the shoots are at the same level as they were originally. Place the newly potted plants in a sheltered position until new leaf growth is well advanced and roots are starting to come out of the drainage holes. They are then ready for planting in the garden.

If only one or two new plants are needed, large clumps can be split into 2 or 3 divisions and replanted directly into new locations in the garden – ensure the divisions are well watered while they establish themselves in their new locations.

It is also possible to divide clumps into sections containing only a single shoot and some roots – in this case the small divisions are potted up into small pots and placed in a glasshouse or similar humid environment until new root growth occurs. They can then be gradually hardened off and potted into larger containers.

Conostylis species seem to be more difficult to divide successfully than Anigozanthos. With Conostylis, best results will probably be with larger divisions.

Tissue Culture

Tissue culture is a plant propagation method that uses plant cells taken from stems, leaves, or other parts of a parent plant to produce new plants. The cells are placed on a nutrient medium under sterile conditions in a laboratory. Using this method, large numbers of clones of the original plant can be produced quickly.

Although this is not a procedure that is practical for the home gardener, it is an important propagation method, particularly with Anigozanthos and Macropidia. Virtually all of the colourful kangaroo paw hybrids that are available in nurseries are produced using this method.

General Propagation

Further details on general plant propagation can be found at the Society’s Plant Propagation Pages.

Kangaroo Paws & Relatives – Cultivation

Introduction

Of the Australian members of the Haemodoraceae, only species and cultivars of Anigozanthos, Conostylis and Macropidia are generally found in cultivation although other genera may be grown by enthusiasts. Of these, only Anigozanthos has received any attention from plant hybridists – interestingly, a few natural hybrids between Conostylis species have been recorded, which may mean that hybridization will create hardier plants of this genus in the future. Species of Haemodorum are also rarely seen in cultivation although the horticultural potential of one species, H.coccineum, is being investigated for the cut flower industry.

Colourful kangaroo paws. ‘Yellow Gem’ (top); ‘Bush Inferno’ (bottom) Photos: Brian Walters

Although many members of the Kangaroo Paw family have proved to be easy to grow in cultivation over a wide range of climates, many others have proved to be a cause of frustration. The origin of most species in a dry Mediterranean climate seems to be the key factor in successful or unsuccessful, particularly the way adapt to climates of higher rainfall, especially in summer. Development of Anigozanthos hybrids has gone a long way in addressing this problem as far as that genus is concerned.

As a general rule, members of the family require the following combination of conditions:

• Excellent drainage – they will not tolerate waterlogging although A.flavidus will tolerate less than perfect drainage.
• Plenty of moisture when the flower buds are forming – lack of sufficient water during this period can cause the stems to form permanent bends and the flowers to abort.
• Good light – the more sun the better.
• Sandy soils or sandy loams

How strictly one needs to adhere to this regime varies from species to species. As a general guide, in areas of high summer humidity (eg. eastern coastal Australian northwards from the NSW south coast) most success will be achieved with Anigozanthos flavidus in its various forms, hybrids based on A.flavidus (see table), Conostylis candicans and Conostylis aculeata. Other species and hybrids can be successful but their cultivation will be more challenging and it may be advisable to grow them in a container. Species such as the magnificent red and green kangaroo paw (A.manglesii) and the green kangaroo paw (A.viridis) usually germinate readily from seed and will flower in their first season – these could be treated as annuals or biennials in humid climates. In less humid districts, a much wider range of species and cultivars can be expected to succeed.

Hardy Anigozanthos hybrids and cultivars based on A.flavidus *

As many the members of the family are usually small and take up little space in the garden, they make excellent feature or rockery plants (the latter position also helping with good drainage), especially in small gardens. It has been noted that cutting the stems after initial flowering will promote further flowering that season (thus extending the flowering period).

A further benefit of Anigozanthos species and cultivars is their attraction to honey eating birds.

Pest and Diseases

Kangaroo Paws (and their relatives) are subject to a number of pests and diseases which can affect their successful cultivation. Of these, the ink-spot (shown left) and rust diseases are probably the most serious. These are discussed under the “Kangaroo Paws: Pests and Diseases” tab.

As a general rule, however, the problems caused by these diseases can be minimized by growing plants suited to the climate and by ensuring that plants are grown in an open, sunny position with good air circulation so that the foliage does not remain moist for long periods.

Weed Potential

Like any plants grown out of their natural habitat, members of the Haemodoraceae have the potential to become weedy in favourable environments. However, the only known problem with the Australian species is a report of Anigozanthos flavidus invading natural areas in the northern suburbs of Sydney (specifically, Ku-ring-gai Wildflower Garden at St Ives). This suggests that this species should be closely monitored in near-bushland areas in temperate climates, particularly in moist locations. As noted previously, most hybrids are sterile and do not produce seed so it may be best to grow hybrids (see table above) rather than A.flavidus itself in such areas.

As far as is known there have been no weed problems with A.flavidus or other members of the family in other areas.

Hybridisation

An important trait of the Haemodoraceae seems to be their ability to hybridise readily. Numerous hybrids of the genus Anigozanthos have become commercially available in the last 15 or so years. The main aim has been to combine the hardiness of A.flavidus with the showiness of some of the other species, including the famed A.manglesii (in the form of the hardier A.‘Bush Emerald’).

When selecting kangaroo paw hybrids the best indicator of hardiness lies in the leaf type. Those hybrids with a leathery glossy, mid-green leaf generally have A.flavidus as one parent which generally makes them a much hardier garden plant. Hybrids with a grey green leaf are usually derived from less hardy species and generally will only thrive for one or two seasons in the garden. The latter are probably best grown in containers using a quality potting mix designed for Australian native plants.

Pests and Diseases of Kangaroo Paws

Keith Oliver

The following article is reproduced from the December 1992 issue of the Society’s journal Australian Plants.

I write on this subject not because I am an expert on pests and diseases, but to summarise what is known to me and what I have observed in my own gardens over a period of 28 years and to indicate areas that need further investigation. In particular I appeal for more information relating to the new phenomenon called “Flower Bleach Deformity” or “Flower Abortion” that has appeared in kangaroo paws in recent years.

The kangaroo paws consist of 12 species of perennial herbs native to southwestern Australia. In their natural habitat most of the species are fire opportunists and colonisers of areas of secondary regrowth. They are not long-lived but produce large quantities of seed which is shed each summer and tends to remain dormant in the soil until the area is burned. The autumn after a fire the seed germinates to produce large numbers of seedlings which proliferate for several years before being overgrown by larger and longer lived species. Under these conditions pests and diseases of kangaroo paws tend to be rare. However, in cultivation, in row cropped monocultures or in gardens, where summer watering and the use of fertilisers is normal, and where the plants are exposed to introduced species of snails, slugs and other pests, many problems are encountered.

The species Anigozanthos flavidus is an exception in that it is not short lived. It can live for at least 30 years in cultivation, possibly for much longer and it is an exceptionally vigorous, hardy and disease free species that has been widely used in breeding the hybrid kangaroo paws that are now widely grown, both within Australia and in other countries¹. Careful selection from the hybrid progeny of A.flavidus yields plants that have good disease resistance and which are little eaten by snails. They are also hardy and vigorous and live much longer than most species of kangaroo paws.

Slugs and Snails

Control of Snails and Slugs is achieved by:

• The slash and burn method of growing (see below) may give at least partial control of snails and many other pests and diseases of kangaroo paws.
• Elimination of potential breeding sites, rockpiles, hedges, ground hugging creepers, rubbish and rough weedy areas, etc.
• Khaki Campbell or Indian Runner ducks give good control.
• Beer traps and sawdust barriers etc., are useful in small areas.
• Baits of Methiocarb (pellets) and metaldehyde (pellets, powder or paste).
• Sprays such as Bordeaux mixture, methiocarb or metaldehyde.

Caterpillars

The damage caused by caterpillars can usually be distinguished from snail damage in that the caterpillars do not eat into the leaf deeply enough to expose the vascular bundles, as snails do, and that snails tend to eat away long strips of tissue, not irregular circular or oval areas. Hand plucking may suffice for small areas. A selective insecticide for leaf eating caterpillars is Dipel® (Bacillus thuringiensis) which is a highly effective stomach poison for caterpillars but is non-toxic to other insects, fish, birds and mammals.

Other stomach action insecticides include Endosulfan, Fenthion (Lebaycid®) and Rotenone (Derris®). These must be eaten by the pest before they are active, so are useful against foliage chewing insects.

Aphids

It has been reported that kangaroo paws can become infested with aphids during the spring or autumn². Control by spraying with Metasystox® or Rogor® is recommended. I personally have rarely seen aphids on kangaroo paws and tend to think that they may only occur on excessively soft growth.

Leaf Miners

These are also outside of my experience but have been reported on kangaroo paws². Control is with Metasystox® or Rogor® when the larvae are active (winter).

Ink Disease or lnkspot Disease

This has been described as a hypersensitive host reaction to several species of fungi, early workers implicating Mystrosporium adustum3 or Drechslera iridis⁴ but later work has attributed the disease primarily to Alternaria alternata^5,6,7.

Species of kangaroo paws differ in their susceptibility to this disease. Anigozanthos manglesii and A.gabrielae are usually killed by the disease while A.viridis, A. pulcherrimus and A.rufus are less affected and A.flavidus is highly resistant. Other species are susceptible in varying degrees.

It is important to note that different isolates (or races) of Alternaria alternata from kangaroo paws differ in their virulence and that each species of kangaroo paw varies in its susceptibility to many of the different isolates. This complicates the breeding of resistant hybrids or varieties as although the fungus is ubiquitous, apparent resistance in particular plants may not persist against a wide range of fungal races.

The symptoms of ink-spot disease vary from brown sunken lesions with some chlorosis and a black rim, to black lesions, or to large black lesions (the rare “big blotch” form) that is seen even on the stems of inflorescences, causing withering of the stem and destruction of the flowers. These symptoms are easily confused with other blackening or the leaf tips or spots on the leaves due to such things as water stress, damage by insects and by other physiological and environmental stresses, so that great care is needed in diagnosing ink-spot disease.

Rust

Unlike the ink-spot fungus, the rust fungus Puccinia haemodora cannot live as a saprophyte (i.e. it cannot live on dead plant tissue) for a part of its life cycle but must always be a parasite (i.e., live on living plants). It has different races and these are often specific to a particular species.

Anigozanthos flavidus seems to be immune to rust attack. A.pulcherrimus and A.rufus may also be resistant⁸, but most of the other species are susceptible. In my experience A.humilis seems to be particularly susceptible. When A.flavidus is crossed with other species the resultant hybrids are variable but many seem to be highly resistant to rust, but A.humilis x A.flavidus hybrids are often susceptible to rust.

Rust disease of Kangaroo Paws is evident as small (approx. 2 mm diameter) reddish brown pustules on the leaves, which usually become more and more dense until the plant is killed. Rust is rare on, if not absent from, wild populations of kangaroo paws, but is a serious disease of cultivated kangaroo paws.

Rust Immunity?

The story is told of some researchers in an eastern Australian state who innoculated plants of Macropidia fuliginosa with rust taken from Anigozanthos manglesii, and finding no infection then concluded that the former species is immune to rust disease. This is clearly untrue, because at this same time rowcropped M.fuliginosa in Western Australia was being devastated by rust. Also from my own experience I had hybrid plants that had survived trouble free for about 12 years, but which were quickly killed when a suitable race of rust attacked them.

Control of Ink-spot and Rust Diseases of Kangaroo Paws

Spraying with Mancozeb® is recommended for ink-spot disease and spraying with Baycor® is recommended for rust. These may not be fully effective in preventing the diseases. Growing disease resistant hybrid plants is a good solution but there may be a disadvantage from irritant hairs on the stems of A.flavidus hybrids if large areas of flowers are to be picked.

Control of Pests and Diseases by the Slash and Burn Method

In the cemetery at Gingin there are populations of A.manglesii and A.humilis which have been slashed and burned in late spring or autumn every year but one since 1973 and probably since the early 60’s (Stephen Hopper, pers. comm.). Under these conditions these crowded populations of kangaroo paws have kept remarkably free of pests and diseases. When I thoroughly checked the area in September 1990, I could find no trace of disease and almost no pests, only a very few flowers showing some insect damage.

Slashing and burning of plants after flowering in late summer to autumn will reduce the innoculum load and give the plants a “clean start” for the following year.

[The accompanying photo sequence shows this method applied to a diseased hybrid kangaroo paw which had been severely attacked by ink disease (note the barrier erected to protect nearby plants). Fresh foliage was produced by the plant over the following weeks (Photos: Brian Walters)]

Dixon⁸ recommends similar treatment for many species but notes that a slow hot burn can kill the plants and also that in the case of plantation grown M.fuliginosa slashing and burning can cause heavy losses. A.flavidus hybrids respond well to slashing but there is no data concerning their response to burning.

Flower Bleach Deformity of Kangaroo Paws

The first symptom is some loss of pigmentation in the developing flower buds, followed by total loss of pigmentation, over all of, or over large areas of the buds, giving them a white colour. This is accompanied by abortion of the entire inflorescence. Usually only some of the stems on any one plant are affected and only more or less randomly scattered plants are affected. Following the abortion of the primary inflorescence a secondary inflorescence will often develop from a lower node of the primary inflorescence stem and so far as has been observed these nearly always develop normally.

Many reasons for this strange disorder have been suggested or advocated, some of these are: adverse weather, too hot, too cold or too changeable; nutritional imbalance, manganese toxicity, copper deficiency; genetic faults in plants; weakness induced by tissue culture, etc. In my opinion, these are all untenable. There has always been adverse weather on occasions and plants have been grown on many soils for many years, but no flower bleach has occurred. Also flower bleach has occurred on seedling plants and on plants dug up in the wild as well as on tissue cultured plants.

Most biologists are fairly certain that it is not caused by a fungus or a bacteria and after discussion, I have formed this hypothesis:

1. It is caused by a pathogen that is probably new to Western Australia, or even to Australia;
2. The pathogen is probably a mycoplasma-like organism (MLO)***.
3. The vector is possibly a green leaf hopper that is occasionally seen sucking sap from soft young flower stems.

Plants affected one year may be clean the next year, only some stems on a plant are affected and clean shoots grow from a lower node of affected stems. All of this indicates that the MLO is not systemic.

Spraying with copper oxychloride is reported to cure the problem although the work did not include unsprayed control plants. As there is circumstantial evidence against the disorder being caused by a copper deficiency and as it is reported that the copper must be sprayed onto the leaves and not added to the soil it is thought that the copper may make the stems either unpalatable or poisonous to the insect vectors, or that in some other way the copper prevents infection by the MLO.

References

1. Oliver, K. R. (1991). Hybrid Kangaroo Paws. Australian Plants 16: 116, 53-60.
2. Reid, A. (1988). Cultivation of Kangaroo Paws. Farmnote No. 54/88, Western Australian Department of Agriculture.
3. Smith, W. T. (1963). The Ink Disease of the Paws. Australian Plants 2:16, 115.
4. McMaugh, J. (1985). in What Garden Pest or Disease is That? Weldon Publishing, Willoughby, New South Wales.
5. Sivasithamparam, K. and Watkins, P. A. (1982). Alternaria alternata as a causal organism of ink-spot disease of Anigozanthos spp. in Western Australia. Australian Plant Pathology 11:18.
6. Sivasithamparam, K. (1985). Diseases. In Horticulture of Australian Plants. (eds B. Lamont and P.Watkins). Pp. 99-102. Western Australian Department of Agriculture, South Perth.
7. Verhooght, M. M. and Sivasithamparam, K. (1986). Ink-spot disease of ‘Kangaroo-paws’ (Anigozanthos Labill. and Macropidia Drumm. ex Harv.) in Western Australia. Crop Research 26: 49-55.
8. Dixon, I. B. (1991). Kangaroo Paw. Australian Plants 16: 116, 77-87.
9. Ulrike Schaper and R. H. Corverse (1985). Detection of Mycoplasma-Iike Organisms in Infected Blueberry Cultivars by the DAPI Technique. Plant Disease 69: 193-196.

Kangaroo Paws & Relatives – Further Information

Most books dealing with Australian native plants will contain useful information on the botany and horticulture of various members of the Haemodoraceae, particularly the kangaroo paws. Some of the most detailed references are listed below.

Books:

• Elliot, W. R and Jones D (1980-1997), The Encyclopaedia of Australian Plants, all volumes, Lothian Publishing Company Pty Ltd, Melbourne. (Note that Volume 2 (A-Ca) was released prior to the advent of many kangaroo paw cultivars, which have been since published in a supplement).
• Hopper, S (1993), Kangaroo Paws and Catspaws, Department of Conservation and Land Management, Western Australia.
• Wrigley, J and Fagg, M (1996 – 4th ed), Australian Native Plants, Collins Publishers Australia.

Journals:

Several issues of the Society’s journal “Australian Plants” are particularly useful for those interested in kangaroo paws and their cousins.

• Vol.10 No.82 December 1979; Australian Haemodoraceae (particularly Anigozanthos); entire issue on propagation, cultivation, hybridisation, taxonomy
• Vol.10 No.82 March 1980; Conostylis; Propagation, cultivation, taxonomy; The Conostylis aculeata group.
• Vol.14 No.116 September 1988; Conostylis; Description of all species.
• Vol.16 No.126 March 1991; Anigozanthos; entire issue on cultivation and hybridisation.
• Vol.16 No.128 September 1991; Hybrid Kangaroo Paws – experiences in cultivation.
• Vol.17 No.133 December 1992; Kangaroo paws – Pests and Diseases; “Bush Gem” Kangaroo Paws.
• Vol.19 No.154 March1998; Kangaroo Paws – What colour would you like?.
• Vol 20, No.164 September 2000; Kangaroo Paws in the Olympic Bouquet.

Internet:

• Growing Native Plants – a series of plant profiles by the Australian National Botanic Gardens; includes notes on the cultivar “Dwarf Delight”.
• Kangaroo Paws – notes on propagation and cultivation by the Australian National Botanic Gardens.
• Kangaroo Paw Maintenance
• Key to the Haemodoraceae of Western Australia – online identification resource
• Paws for Reflection – selecting and growing kangaroo paws
• Smoke Stimulates the Germination of Many Western Australian Plants, by K.Dixon and S.Roche – contains useful information on research into many plant genera including some of the Haemodoraceae.