Category Archives: Plant family

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

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.

Oregano

The labiate flowers of thyme are typical Lamiaceae

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

Lavender

Lavender

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

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.

Rutaceae-4713

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.

Rutaceae-4582

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

 

Getting to know plant families, Myrtaceae

Eucalyptus smithiiI have a theory. The reason a plant such as Agapanthus is so popular is that people are familiar with it and they know its name. Though I would love to see it in its native South African setting, I dislike the pervasiveness of the plant.

But, to explain the theory, at one point in time, I would visit a nursery and be bewildered by all the plants for sale and not know where to begin. The position of ignorance when faced with so much choice was daunting. Knowing the name of something even if it was Agapanthus can be reassuring.

So, I made a conscious decision about fifteen years ago to learn more about plants and their names. Although I am more interested in native plants, I like all plants. Where they are from? What other ones are they related to? Knowing what they are and what plant family they belong to helps.

Family → genus → species

I grow chilli and capiscum plants for example, they are part of an often poisonous plant family Solonaceae. I think of the heat of the chile as a form of plant defense like the poisons in other species such as Datura from that family. Within the family is an important genus, Solanum, which contains such species Solanum tuberosum – the potato, Solanum lycopersicum – tomato and Solanum melongena – eggplant all from the Americas and apparently quite closely related.

For me, this relationship is based on recognition and memory. I am not sure yet how to recognise any of the Solanum species except on remembering what the plant is, what the flower looks like and what family it is from. Fortunately, other plant families have distinctive attributes and are quite recognisable.

Leptosermum squarrosum

Leptospermum squarrosum

I learnt early on that plants in the Sydney Region are often dominated by a small a number of families including Myrtaceae. Myrtaceae contains our iconic gums or eucalypts.

An Angophora capsule

They are quite clearly recognisable by their leaf shape and also have a capsule, which is also a distinctive feature of many plants in the Myrtaceae family and which usually persists on the plant long after it has dropped the seeds contained inside it. So, Leptospermum – Tea-trees, Melaleuca – Paperbark, Callistemon – Bottle-brush all have this dry capsule containing the seeds. Some that we are familiar with such as Kunzea Ambigua – Tick Bush, don’t have a capsule that persists. However, Myrtaceae has another great identifying feature; the flowers have lots of stamens. It is the stamens that are giving Eucalypts their distinctive look. So, even Kunzea can be recognised, no capsule that lasts, but lots of stamens.

Myrtaceae-7804_1A species which I saw on the weekend at West Head in  Ku-ring-gai Chase National Park, I wasn’t sure of was Darwinia fascicularis. It is a species in another genus, Darwinia, of the family Myrtaceae. However, the spikes aren’t stamens at all, the anthers are hidden and the protruding bits are the style, but they are very beautiful plants.

Which brings me back to Agapanthus. Why when we have so many great plants, over 20000 in Australia, do we have to have garden’s full of the South African species, Agapanthus? I have my theory and if people learn the name of a few plants they might not just not order the ones that know.

Resources

If you want to pursue an interest in plant identification, these are some excellent resources,

Robinson, L.  Field Guide to the Native Plants of Sydney, 3rd Ed, (2003). Kangaroo Press.

I have a large colour reference  from Fairley and Moore which I use to complement Robinson’s book and they have more recently bought out a field guide sized, reference in colour.

Fairley, A and Moore, P (2010) Native Plants of the Sydney Region.CSIRO Publishing.

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.