Оңтүстік Аустралияның Варратасы: Сипаттама және Түрлері

Genus of plants in the family Proteaceae from southeastern Australia

The waratah (Telopea) is an Australian endemic genus of five species of large shrubs or small trees, native to the southeastern parts of Australia (New South Wales, Victoria, and Tasmania). The best known species in this genus is Telopea speciosissima, which has bright red flowers and is the New South Wales (NSW) state emblem. The waratah is a member of the family Proteaceae, flowering plants distributed in the Southern Hemisphere. The key diagnostic feature of Proteaceae is the inflorescence, which is often very large, brightly coloured and showy, consisting of many small flowers densely packed into a compact head or spike. Species of waratah boast such inflorescences ranging from 6–15 cm in diameter with a basal ring of coloured bracts. The leaves are spirally arranged, 10–20 cm long and 2–3 cm broad with entire or serrated margins. The name waratah comes from the Eora Aboriginal people, the pre European inhabitants of the Sydney area.

The genus Telopea belongs to the plant family Proteaceae. Within the Proteaceae, their closest relatives appear to be the genera Alloxylon (tree waratahs), Oreocallis and Embothrium, a group of generally terminal red flowering plants that skirt the southern edges of the Pacific Rim. Together they make up the subtribe Embothriinae. The genus was first described by Robert Brown in 1810 from the type species Telopea speciosissima. There are five species of plant within the genus, all of which readily hybridize in cultivation. There are two main branches, with one being the species pair of T. speciosissima and T. aspera, with the other lineage giving rise to T. truncata first, then T. oreades and T. mongaensis. The speciosissima aspera lineage (clade) has two synapomorphies—distinguishing common characteristics presumed not present in ancestors—leaves with toothed margins, and large red involucral bracts. The truncata oreades mongaensis lineage has flowers that open from the centre to the edge of the inflorescence (basitonic) rather than the reverse (acrotonic), which is a feature of the speciosissima aspera clade and more distant relatives.

The propagation of waratah for commercial production is relatively easy in comparison to other stages of the growth cycle. Plants are usually propagated from cuttings, fresh seed or stored seed. Fresh seed has a good germination rate but deteriorates fairly rapidly unless stored at low temperature and low humidity. Dry seed will last a few years in refrigerated storage but should be treated with a general purpose fungicide prior to storage and at propagation to ensure good germination rates and healthy seedlings. The best time to take cuttings is when the plant is experiencing a flush of growth. The cuttings are taken from firm wood from the last twelve months growth. If plant material is scarce, single nodes can be used for cutting propagation. Other methods of propagation that are successful but not widely used for commercial production include grafting and tissue culture. Stock for grafting is vigorous and as such is labour intensive in constant control of stock regrowth from the lignotuber. As such, it is not a recommended method but is useful for the fast growth of limited material. Rootstock and scion combinations are used for many woody perennials to provide the necessary mix of floral or fruit characteristics and cultural requirements. Tissue culture is very labour intensive and would likely only be used in the case of rapidly increasing the number of plants from limited or valuable material. The process is complex though as different clones require different optimal culture conditions requiring different developmental work for each clone. There also exists problems with hardening off, with roots and leaves produced in vivo dying off on planting out. For Telopea plants propagated from seed, the transition from seedling to flower takes about 5 years. Cuttings may take only 2 years. The most common form of propagation is from seed, however, certain varieties and cultivars must be propagated from cuttings if the grower wishes the plants to remain true to form. Fresh seed has a higher viability than cuttings and will germinate 2–3 weeks after sewing.

The overall cultivation of the waratah as a single process is a tricky one as flowering time, number and quality are easily affected by changes in the plant environment. These factors must be considered as early as prior to buying land for production. North facing aspect ensures a maximum of sun exposure. A combination of northerly, easterly and westerly aspects will spread the flowering time with the western slope flowering slightly later on. As the location approaches the equator, flowering time will be earlier. Elevation also has to be considered as it will affect temperature, a major influence on flowering time. More flowers will be produced in full sunlight although better quality flowers are found in the shade. Paul Nixon (1997) in his book ‘The Waratah’ claims that ‘the ideal situation is to have rich, well drained, deep soil with a north easterly aspect giving the plants full sun until the flowers buds have initiated and then put shade cloth over the bushes until they have flowered’. A primary consideration for cultivation is water drainage. The waratah naturally grows in poor, sandy soils where it thrives due to the soils excellent water draining properties. Drainage properties can be linked to aspect and as a result plants grown on a north easterly aspect will generally flower 1–2 weeks earlier than a westerly aspect at the same location. Watering systems must also be carefully considered to coincide with correct drainage. As an Australian native the waratah is a sturdy plant well adapted to coping with harsh environments and low rainfall. Watering systems are still necessary for cultivation in order to produce a reliable crop and a quality bloom. In the wild the waratah has become adapted to growing in nutrient poor soils leading many people to believe that this is what is necessary for the development of the plant. Fertilisers are not necessary for the development of the plant but the waratah has been shown to be receptive to some treatments. Many native plants have been known to have poor establishment in soils with high levels of nitrogen and phosphorus. This coincides with the observation that fertiliser application immediately after transplant of waratahs in the field often leads to high mortalities. Other studies have reported a strong growth response to high nutrient levels, particularly phosphorus. As yet, the details of this response are not yet clear and suggest a complex nitrogen phosphorus relationship. Earlier work (1963) on related species, had indicated that fertiliser application may hasten maturation and give early flowering. If fertiliser is applied, drainage properties of the soil mean that nutrients are quickly leached and so the best application method is multiple applications at critical stages in development such as flush periods. Pruning is a very important consideration for the commercial growth of waratahs in the effort to design a shape for the plant that will encourage the maximum production of saleable blooms. The aim is to get as many growing tips as possible as it is on these that the flowers will develop. With the correct mix of factors for cultivation it is possible to produce up to sixty blooms per plant per year. This could translate to up to 20,000 to 50,000 blooms per ha. Waratah inflorescences are harvested when 0–50% of flowers are open, although inflorescences with 0–5% of flower open have the longest vase life and least opportunity for bract damage in the field.