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Thomasias and Their Close Relatives

Janet Atkins

Editor's Note: The following article has been edited slightly to include Lysiosepalum involucratum, a small Western Australian plant which is becoming common in nurseries and gardens in the eastern states, and which is proving to be one of the most adaptable of this 'Thomasia-group' for gardens in a range of soils and climates. Although the article deals with Western Australian members of this group, these are some eastern species and a photo of one of these has been included.

Guichenotia macrantha
  Guichenotia macrantha
Photo: Tony Cavanagh
Some of the most difficult spots to deal with in any garden are dry and partially shady areas. However, there is a group of poorly utilised and mostly Western Australian plants that can do very well in these situations. Many will also grow well in full sun.

The Thomasias and their close relatives Guichenotia, Lasiopetalum and Lysiosepalum are wonderful small to medium woody shrubs that flower prolifically. Flowers range in colour from purple through pink/mauve and creamy white. Many of this group are also worth growing for their foliage alone; it is often soft and velvety and ranges in colour from lime green (Thomasia solanacea) to soft grey/green (Thomasia macrocarpa). Generally these plants do not have a common name so it is necessary to persevere with the scientific one.

Most are proven performers in the dry summers of recent years and are quite happy in the partial shade of trees and have survived in my Perth Hills garden with little to no water throughout the summers of the current dry period.

Thomasia purpurea has flowers in purple clusters for most of the spring months and is a small compact, rounded shrub of just under 1 metre. Like a number of this group it responds well to a light trim with the hedge shears.

Thomasia solanacea, with its beautiful foliage can grow to 2 metres, which makes it one of the larger plants in this group. One the hottest summer days its thick light green foliage is a bright spot in shady areas. It also responds well to the hedge shears treatment.

Some members of the 'Thomasia-group'
Thomasia grandiflora
Thomasia grandiflora
Thomasia grandiflora
Thomasia grandiflora
Thomasia macrocarpa
Thomasia macrocarpa
Thomasia pygmaea
Thomasia pygmaea
Thomasia rhynchocarpa
Thomasia rhynchocarpa
Lasiopetalum ferrugineum var. cordatum
Lasiopetalum ferrugineum
var. cordatum
Lysiosepalum involucratum
Lysiosepalum involucratum
Photos: Brian Walters; Santa Cruz Arboretum (T.grandiflora bush)

Some of these plants may be a little difficult to find, even in specialist Australian Plant Garden Centres, but the only way to have more of them produced is to start asking.

Thomasia pygmaea

Jeanette Closs

Thomasia pygmaea, a member of the Sterculiaceae family, is one of the cutest little plants that you will see anywhere. Yet in my vast collection of Australian plants books, I can find little description of this little gem from Western Australia. The Australian Plants Journal, which has been published more or less regularly since 1959, has one photo and a couple of mentions of the plant growing in people's gardens, but no description. Grow What Where lists it and places it in 13 different categories. Some of the categories that Thomasia pygmaea is listed in are rockery plants, plants for heavy and clay soils, shady dry soils and sandy soils - so it should tolerate most soils. Also it is moderately lime tolerant, usually frost resistant and summer flowering. It is a good container plant - that's where mine is as I don't find it as hardy as Grow What Where indicates.

It certainly is small, but I think that I have seen it covering an area about one metre wide. The interesting thing about this plant is that it appears to have rusty 'measles'. Every part of the plant, the stems, the small heart-shaped leaves (but mostly on the lower surface) and the small mauve Chinese lantern-type flowers are covered with masses of reddish-tan speckles.

I find that cuttings are difficult to strike and I have never made the effort to collect seeds. I recommend that if you can get a plant, put it in a container in part shade and place the container on a table or bench, because to see its true beauty it needs to be at eye level.

From Eucryphia, newsletter of the Australian Plants Society (Tasmania), January 2003.

Guichenotia macrantha, with its open graceful growth habit and beautiful clusters of pendulous, papery pink flowers is one plant that should be quite easy to obtain. This plant does best with full sun with an under planting of very small shrubs or clump plants.

Some suggestions to start with:

Thomasia foliosa0.5m x 0.5mMulti-stemmed rounded shrub; whitish pink flowers May-Nov
Thomasia macrocarpa1.5m x 1.5mLarge clusters pink/purple flowers in spring; grey-green velvety leaves
Thomasia purpurea0.8m x 0.8mCompact rounded shrub; purpleflowers
Thomasia pygmaea0.3m x 0.5mLow spreading woody shrub with mauve/pink flowers
Thomasia solanacea2.0m x 1.5mWhite flowers spring; dense bright green foliage
Lasiopetalum bracteatum0.8m x 0.8mCompact shrub; velvet foliage; clusters of starry pink flowers in spring
Lysiosepalum involucratum0.8m x 0.8mBushy shrub with greyish foliage; mauve/pink flowers over a long period in spring
Guichenotia macrantha1.5m x 1.5mStriking plant; large flowers for this group. Does well in most soils
Guichenotia ledifolia1.5m x 1.0mDense shrub; grey green narrow leaves; prolific quantities of pink flowers winter/spring. Grows well in coastal areas

Planting in autumn or early winter should see these plants doing very well with little water requirement the following summer. Some improvement of poor sandy coastal soils may be beneficial but, in the heavier soils of the Perth Hills, a small dose of slow release fertiliser at planting is all that is necessary. Although most will do very well in areas with partial shade some have problems in heavy shade. If too crowded and with poor air circulation leaf fungal problems, such as rust, may develop during the wetter periods of spring.

All these plants would also be well suited to cottage style gardens and most will do well as potted specimens in the appropriate sized container. All of these thomasias and their relatives are local to Western Australia and well adapted to this climate. It is unfortunate that at this point of time they have been little used in gardens of Perth and the South West.

From the newsletter of the Wildflower Society of Western Australia, February 2004, via the newsletter of the South Australian Region of the Australian Plants Society, August 2004.

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