Autumnal Acanthaceae

Sunday, 28 April 2019

Pachystachys lutea growing in the Royal Botanic Garden Sydney

It's hard to believe that it has been seven years since I launched my little booklet Meet the family Acanthaceae onto the unsuspecting public. A lot has happened in my gardening journey since then, but I am still a huge fan of these easy-to-grow, warm-climate plants. In the intervening years I have trialled a few more members of the family to see how they fare in Sydney. Some are just too cold sensitive to survive our winters, but only the whole, many do very well. I feel I understand the needs of these plants better these days: where once I thought they would all flower well in shade, for example, I now realise that some definitely do better with more sun.

Brillantaisia ulugurica

There are Acanthaceae plants for every season in Sydney and autumn sees a number of these plants in bloom. Some are continuing on from summer (or even earlier!), such as Brillantaisia ulugurica (syn. Brillantaisia subulugurica), with its tall panicles of purple-blue, vaguely orchid-like flowers; Justicia betonica, with its seemingly never-ending upright spires of white-bracted flowers (one which does seem to do better in a sunny spot!); the plump pink or white plumes of Justicia carnea; and the profusion of red trumpets of Ruellia elegans - wonderful, worthwhile plants for colour in our gardens.

Rhinacanthus beesianus

Other begin their blooming period in autumn. One of the most spectacular is Megaskepasma erythrochlamys (ht 2-3 m, often called Brazilian red cloak), a tall shrub with vibrant crimson bracts in bold panicles held above enormous, deeply veined leaves. It will flower in sun or shade, though a sunny spot seems to give the most profuse blooms. Rhinacanthus beesianus (ht 2 m), another large shrub, comes into flower now. In the seven years since I wrote the book, a number of Acanthaceae plants have had name changes, and this is one of them. It was originally identified only as 'Pseuderanthemum species' on its name plaque in the Royal Botanic Garden, Sydney. The new name was identified a few years ago. The plant, whatever its name, is lovely, with clear white flowers shaped liked scalloped shells. The blooms are lightly fragrant. This shrub is another which will tolerate part-shade but flower best with a decent amount of sun.

Strobilanthes cusia

Another pretty Acanthaceae shrub for autumn is Strobilanthes cusia (ht 1.5 m, previously known as Strobilanthes flaccidifolia), which has weeping stems covered in petite pink trumpet flowers. This one will bloom in shady places, in very ordinary soil, and even with root competition from nearby trees. A smaller shrub is Barleria cristata (ht 80 cm), which I have only starting growing in recent years. In autumn it is smothers in simple, five-pedalled flowers in colours of purplish-blue, white or white with lavender stripes. It grows in sun or part-shade.

Ruellia makoyana growing with rhizomatous Begonia cultivars

At groundcover level, cute Ruellia makoyana (ht 30 cm, sometimes known as the trailing velvet plant) has trumpet-shaped, carmine-pink flowers held above silver-variegated foliage. It will grow in dry shade and forms a wide carpet, complementing such shade-loving shrubs as cane begonias, Sasanqua camellias and the many Plectranthus species and cultivars, all blooming brilliantly at the moment.

I have recently updated my Acanthaceae booklet to reflect the changes in names over the past seven years, and to include some new plants that I have since encountered, as well as my altered thoughts on the cultivation of some of the family members. More photographs have also been added. It is now presented as a 27-page, A4-sized downloadable e-book that can be printed at home. See here for details.

Plant of the week

My previous blogs at this time of year:
2009
26 Apr
2011
24 Apr
2012
29 Apr
2015
26 Apr
2017
30 Apr

Reader Comments

  • By Shaun - 2075 (Zone:10 - Warm Temperate) Monday, 29 April 2019

    After a gardening article in Sunday paper a year ago I tracked a Brillantaisia ulugurica to Growing Friends at Botanic Gardens. I love the orchid like flowers and it sits happily at the back of a hole in my back garden but I have just struck a few more (it"s willing) to bring it forward into more sun to be aware of its gorgous leaves and flowers! I discovered the Huge Garden Sale in Lane Cove yesterday, what a day out!! Glad you were able to get that Brillantaisia at the Growing Friends nursery - they have a fantastic range of Acanthaceae. Great you got to the plant sale last week. I believe they raised a wonderful amount for the National Breast Cancer Foundation charity that they support. Deirdre

  • By Kerrie - 2104 (Zone:10 - Warm Temperate) Monday, 29 April 2019

    Yes I got Brillantaisia ulugurica from Growing Friends too! I just adore it! I got Ruella elegens from Growing Friends as well. I also have Justicia Carnea & Ruellia makoyana, both from cuttings from an old garden.I just LOVE Salvias! Last week at the local hardware shop I picked up one called Black & Bloom with gorgeous black & purple flowers. Glad you like those Acanthaceae plants - they are some of my favourites - and of course salvias too! Deirdre

  • By Kerrie - 2104 (Zone:10 - Warm Temperate) Monday, 29 April 2019

    Oh & I"ve also got Brazillian Cloak plant. The flowers are stunning! Yes it is amazing! Deirdre

  • By Ruth - 3185 (Zone:10 - Mediteranean) Monday, 29 April 2019

    I wonder if your P.ambiguous is P. suavolens that I grow. I think they may be different - Plectranthus suaveolens seems to be a name sometimes used for something very like Plectranthus parviflorus, which I have listed in my Plant Directory. The flowers on the one I know as P. ambiguus are a much deeper purple colour and bigger. Deirdre

  • By Sue - 2074 (Zone:10 - Warm Temperate) Monday, 29 April 2019

    An interesting family so I bought your book! Will be moving my pachystachys into more sun after seeing the RBGS pic. I was surprised to see how many of the family I actually had. I bought Ruellia dipteracanthus some time ago from the Friends but am now a little nervous as it seems to be a thug. Have you experienced this problem? Do not worry too much about that Ruellia -- it is great for a dry, difficult spot. Just don"t plant it in a good area as it does tend to spread a bit and it is not one of the more showy ones. However, I still have it and it fills a niche. Deirdre

  • By Pamela - 2158 (Zone:10 - Warm Temperate) Saturday, 04 May 2019

    I feel I need to start a library of the printouts of your blogs Deirdre as they are my constant go to for identification.Id only just started to remember Strobilanthes flaccidifolia now S.cusia, how do you keep up?Feel another trip to the Botanic gardens looming, would like to find a spot for Megaskepasma and the Rhinacanthus. Ive underplanted a ficus in a large pot with Ruellia makoyana and Tradescantia zebrina which looks lovely.Thrilled i can grow many of Acanthaceae family in my garden. Thanks so much, Pamela. You have some great Acanthaceae in your garden! Deirdre

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