The Queensland Gardening Pages

Tibouchina

Tibouchina cultivars are very popular in South East Queensland, 'Alstonville' joining Jacaranda and Poinciana as signature species in gardens of this region.

As with so many plants which are transported and cultivated all over the world, there's quite a bit of confusion over the identity of varieties, and their correct names. Many of the online references are in Portugese which makes it difficult for an English speaker to invesigate Brazillian sources of information.

This page is a work in progress, and it's hoped to be able to bring you more information and illustrations in future updates. In the meantime, hopefully you'll find something useful here.

Links to relevant webpages on other sites are given throughout the text. See the bottom of the page for details of printed books and printed jounal articles referred to in the text, and more links.

History of Cultivation

Tibouchinas originate in South America. The word itself is derived from the native name in the Guiana region (the countries to the north of Brazil) (Hazelwood, 1968; Harrison, 1967). Tibouchinas are cultivated widely in Brazil. T. granulosa is called Quaresmeira. T. lepidota is called Sietecueros.

(You may sometimes see reference to a species called Tibouchina grandiflora when searching. I'm trying to confirm what other species/cultivars this could be synonymous with. )

In older Australian and New Zealand literature, Tibouchina is also referred to by the older name of Lasiandra. The most commonly cited species prior to the 1980s is the plant variously referred to as Lasiandra macrantha, Lasiandra semidecandra, Tibouchina semidecandra Tibouchina semi-decandra and later, Tibouchina urvilleana.

'Grandiflora' was a popular variety, having larger flowers than the species. A cultivar of Australian origin which is also frequently mentioned is 'Edwardsii'. Victorian nurseryman Edward Edwards, crossed 'Grandiflora' and the species to obtain flowers of a deeper richer colour. 'Edwardsii robusta' was another variety selected for large flowers and vigourous growth. (Herbert, 1958; Harrison, 1967; Hazelwood, 1968)

Although 'Edwardsii' and 'Grandiflora' may have had somewhat more dwarf and compact growth than the species (opinions on the relative merits of each vary somewhat between authors), the "Lasiandras" generally had a poor reputation as plants with straggly growth habit and a need for frequent pruning.

The Tibouchina Revolution in Australia

This began when Australian nurserymen made several garden-worthy selections from various seed imported from Brazil in the 1960s. Particularly prominent in the Tibouchina story are the Dunstan family, who selected and marketed 'Alstonville' and several others. The superior characteristics of the new plants eventually won over gardeners. Today, Tibouchinas constitute one of the most significant groups of flowering shrubs/small trees in gardens of this region.

Students of horticulture interested in researching the history of 'Alstonville' and other Australian cultivars of the period should consult Dunstan (1982), Burke (1984) and Lake (1996). (See list of references at the bottom of this page).

Modern Tibouchina Cultivars

Classed as a shrub by some, it can be trained as a small tree with appropriate pruning. Its small and controllable size has no doubt contributed to its popularity in modern gardens, where there is no longer space for grand tropical flowering trees like poinciana.

Also, many other trees flower in spring or in early summer. Although it can produce some flowers in spring, 'Alstonville' provides a burst of colour in late summer/early autumn. Its namesake Alstonville (NSW), the town near which this plant was developed, has a Tibouchina festival every year in March when the trees are putting on their best display (Remember, this is the Southern Hemisphere).

'Alstonville variegata' is a variegated leaf form. If anyone is still producing this cultivar commercially, please get in touch.

This cultivar is also very popular, but in contrast to 'Alstonville' it is a dwarf shrub, suitable for a garden bed or container.

This cultivar has pink flowers (The original species T. granulosa has purple flowers), and will grow into a tree if left unpruned.

One of the cultivars from the Dunstan family of the 'Alstonville' period, this shrub's flowers open white and darken to through pink with age.

Hazelwood (1968) describes a Brazilian species called T. bicolor, the flowers of which start white and turn to purple as they age. More recent publications refer to a T. mutabilis which has similar characterstics. Perhaps 'Noeline' is a cultivar or maybe just the regular species.

A number of other cultivars have been introduced into the marketplace in Australia since the above releases. Keep an eye on this page for more information on these varieties. Breeders, growers, distributors, or promoters can use this page to advertise their new Tibouchina releases or where to buy them in Queensland.

Cultivation

In the literature, gardeners are generally advised to plant Tibouchinas in well drained, acidic soils and to supply plenty of water and fertiliser. However, Tibouchinas are seen all over Brisbane in situations where soils are probably less than ideal and where they're unlikely to be receiving any supplemental water or fertiliser after establishment. In this region, therefore, they can be considered relatively tough, trouble-free plants for average garden conditions.

Of course, they are more likely to perform at their best with a little attention. They are widely believed to like an acid soil so this should be kept in mind when considering fertilisers, potting mixes and soil amendments.

As with most shrubs, the best time for major pruning is immediately after flowering (the main flowering for Tibouchina being autumn).

Uses in the Garden

As indicated above, Tibouchinas are available in a range of growth forms, so you can select a variety to suit your needs whether it is a flowering tree or a shrubby grouncover. You can also manipulate the form to some extent depending on how you prune.

In terms of style, although the tibouchinas may be classed as "tropical" in terms of their climatic range, the overall look is not particularly "tropical". The flowers, occupying the white - pink - purple range, are "pretty" rather than truly "exotic" in appearance. These trees and shrubs would fit well into a traditional landscape styled after European or North American gardens, but where it's too hot to grow classics like Rhododendron or Prunus. They would also suit a cottage-style garden or simply a purple-flowered colour scheme.

References and other sources of information

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