Eidothea hardeniana and other rare trees in Nightcap National Park, north-east New South Wales

Scientist standing in front of a fallen treeScientists Dr Maurizio Rossetto and Dr Robert Kooyman next to a fallen tree in The Big Scrub, from a recent trip to Nightcap National Park to make the video below. The video production consisted of a crew of one – me! A beautiful place and hopefully an interesting story.

What is the video about?

The National Herbarium NSW of the Royal Botanic Gardens in Sydney has been doing interesting scientific research into rainforest tree distribution and rarity in Northern NSW. They have found links between rarity and the relatively recent local extinctions of large fauna such as the Cassowary. This video features scientists Dr Maurizio Rossetto and Dr Robert Kooyman. As well, it features the recently discovered and extremely rare tree Eidothea hardeniana as well as trees from the Gondwanan family Elaeocarpaceae.


Getting to know plant families, Lamiaceae

Prostanthera striatiflora near Broken Hill
Lamiaceae family member, the species – Prostanthera striatiflora, near Broken Hill

I like it when I understand enough about a plant family to recognise a plant as belonging to it.

Lamiaceae is one family that I get. There are a few reasons.

Rosemary (Rosmarinus) a genus in Lamiaceae

Lamiaceae is also known as the ‘Mint-family’. Mint (Mentha) is a member and like mint most of Lamiaceae’s species have aromatic leaves. And what aromas! Rosemary (Rosmarinus), Thyme (Thymus), Sage (Salvia), Basil (Ocimum) and Oregano (Origanumare all Lamiaceae plants.

The labiate flowers of thyme are typical Lamiaceae

Lavender (Lavandula) you ask? Yes, most definitely Lamiaceae.


But, there are more than 7000 Lamiaceae species worldwide, making it the 7th largest plant family.

One of Lamiaceae’s 44 Australian genera is the native genus Prostanthera or Mint-Bush which has an unbelievably wonderful aroma.  It is a fantastic plant for gardens. Enjoy the smell as you rub up against it or crush some leaves. Prostanthera occurs widely from alpine to arid areas.

Prostanthera striatiflora near Broken Hill
Prostanthera lasianthos near Thredbo
Prostanthera lasianthos near Thredbo

A well known native is Westringia fruticosa which is often used in landscaping, but is naturally found hanging on rocks exposed to the sea in the harshest conditions. Its common name is Coastal Rosemary but unlike Rosemary and most other Lamiaceae species, Westringia fruticosa has no aroma.

Westringia fruticosa
Westringia fruticosa at Wreck Beach, Shoal Bay

The family is quite recognisable. The plant below is growing in coastal heath in Yuraygir National Park on the NSW north coast. It looked to me like Lamiaceae, but I didn’t know the genus or species. I asked Trevor Wilson from the Botanic Gardens in Sydney who is studying the genus Prostanthera and he identified it as Chloanthes parviflora. Chloanthes is a genus of Lamiaceae.

Chloanthes parvifliora - in coastal heathland, Yuraygir National Park
Chloanthes parvifliora – in coastal heathland, Yuraygir National Park

Or in the arid zone another species from a different genus Teucrium occurs – but again the flowers look like Lamiaceae.

Teucrium albicaule cccurs in arid chenopod grasslands
Teucrium albicaule cccurs in arid chenopod shrublands

Lamiaceae flowers are quite distinctive. They are zygomorphic (bilaterally symmetrical) and they are labiate. Labiate means that one or more petals can form a lip (Clarke and Lee, 2002). They have 2 or 4 stamen.

Lamiaceae stems are usually square shaped. If you run your fingers along a stem of Rosemary or Westringia for example you can feel the ridges.

The leaves are usually opposite.

So when I see labiate flowers, I grab some leaves and take in the aroma. I rub the stems – feeling the square shape and think Lamiaceae! 

Prostanthera plant
My favourite – Prostanthera


Some resources

A website with plenty of pictures of Lamiaceae in Australia both exotic and native as well as the butterflies and moths found feeding on them is Don Herbison-Evan’s Butterfly (Lepidoptera) site.

PlantNet, an online reference to Plants of News South Wales http://plantnet.rbgsyd.nsw.gov.au/

Clarke, I and Lee, H (2003) Name That Flower: The Identification of Flowering Plants,  Melbourne Univ. Publishing, 2003 is fantastic for its descriptions of flowers and flower parts.

Trevor Wilson at the Botanic Gardens Sydney is doing a postdoc research on Prostanthera and was very helpful with IDs of plants from photographs.

Other Getting to know Plant Family pages – Rutaceae, Myrtaceae and more are on their way…

Getting to know plant families, Rutaceae

Phebalium squamulosum
Phebalium squamulosum – Harold Reid Reserve, Middle Cove, Sydney

Another significant plant family in Australia and around Sydney is Rutaceae.

Correa alba
Correa alba at Bronte Sydney

So, It is one to learn. It’s fairly easily recognised, it usually features plants that have oil glands on the leaves, when they are crushed they provide an aroma. You can see the oil glands in many of the photos on this page.

All these leaves have oil glands, Pheballium, Eriostemon, Lime, Kaffir Lime, Zieria

Rutaceae also has beautifully arranged flowers.

Boronia falcifolia from Wallum Heath
Boronia falcifolia, from Wallum Heath at Red Rock, NSW

It is economically important because it includes Citrus and landscaping plants like Murraya. It is also conidered important in our understanding of Gondwana but I’ll come back to that.

Limes, Citrus aurantifolia
Citrus aurantifolia, Limes – note the oild glands in the leaves

Flowers are key to understanding and recognising plants. They are incredible organs, highly variable between families but often within families they are pretty consistent. If you can learn to recognise one flower in a family, you can recognise others.

Rutaceae’s flowers are what is considered ‘perfect’. They contain functioning male (stamens) and female (carpels) parts. As well, in Rutaceae they are arranged in a whorl. A whorl means each part is stepped so that it doesn’t overlap the part beneath it.

Crowea saligna, common in Sydney bushland
Crowea saligna – common in Sydney bushland

The flower parts from outside to inside are

Sepals – the leaf like protective bits that cover the growing bud.

Petals – the colourful bits sit above the sepals. In Rutaceae there are just about always 4 or 5 petals. These are radially symmetrical which is known as actinomorphic.

Phebalium squameum, it has 5 petals and 10 stamen
phebalium squamulosum – 5 petals and 10 stamen

Stamens – the male part. In Rutaceae there are either the same amount as petals or double. So if I see 4, 8, 5 or 10 stamens in flowers that are perfectly symmetrical I start thinking thinking Rutaceae. Of course, there are exceptions.

Carpels – the female part which contains the stigma which is adapted to accept only compatible pollen and is joined to the ovary by the style. The Correa alba photo above is the best for highlighting the carpel.

Zieria smithii
Zieria smithii – note the oil glands

Once you recognise the family then you can think about relationships between genera. How, for example, are Crowea, Boronia and Phebalium related to other Gondwanan genera like the South African genus Diosma (pictured below) or Calodendrum. Calodendrum a genus which means beautiful tree contains the gorgeous Cape Chestnut.

Diosma sp.

The Melbourne Botanic Gardens are using Rainforest and Sclerophyllous Rutaceae species in Australia and New Caledonia (also Gondwanan) to uncover relationships and clues to geological histories.

And of course, it can keep you thinking about the Citrus family which is thought to have its origins in China and has been cultivated for the past 4500 years.

Eriostemon australasius
Eriostemon australasius, near Wooli, Yuraygir National Park