Cardwellia sublimis, a giant of the Proteaceae family, was one of the ‘big things’ we encountered during our visit to the Paluma rainforest late last year. Its local name, Northern Silky Oak, harks back to colonial times when its timber with oak-like grain was highly valued for building Queenslander-style houses and furniture

Cardwellia sublimis is endemic to well developed rain forest areas in north eastern Queensland. Some tall specimens may be spotted near the road to Paluma (photo above). Even taller emergent trees almost 40 m high have been reported to occur in optimal conditions.

Cardwellia sublimis has large compound leaves with the leaflets glossy on the upper side and having a golden-brown sheen underneath (photo above).

Cardwellia sublimis produces beautiful panicles of cream flowers (first photo on this page) that are followed by very large brown woody fruits (lower centre of photo above). These fruits remain for quite a while on the tree where they split open to release winged seeds whose dispersal is probably assisted by wind.

Within the rainforest, Cardwellia sublimis tends to blend in amongst other trees and its lofty crown may be hard to spot. Fortunately its large fallen seed cases (photo above) persist for a long time on the ground and provide a helpful clue that Cardwellia sublimis is probably growing nearby.

The seedlings of Cardwellia sublimis have distinctive cotyledons reminiscent of bright green butterfly wings (photo above). Although the seeds are reported to germinate readily in 14 to 24 days, attempts to grow Cardwellia sublimis in plantations have not been successful.

A special shout-out to Earthwatch Australia for organising Bioblitz events this month at various saltmarsh and mangrove areas near Townsville, where participants encountered a fascinating range of lesser-known fauna and flora.

Thanks to Beth for spotting an unusual plant amidst a swathe of low-growing saltmarsh species (photo above) and identifying it as Limonium solanderi. This Queensland endemic was a personal “new species” for most of us.

Limonium solanderi (Plumbaginaceae) has branching inflorescences with small creamy-yellow flowers (photo above) seen in more detail in the first photo at the top of this page.

The angular stems of Limonium solanderi arise from a basal rosette of leaves (photo above). The plant is evidently well-adapted to the harsh saltmarsh environment and might be a nice addition to a coastal garden but it remains to be tested whether it would thrive in a non-saline environment.

Caution: Please don’t let anyone persuade you to grow non-native Limonium species often called “sea lavender” although not botanically related to true lavendar (Lavendula sp). Some introduced European Limonium species have become invasive weeds that are already threatening native coastal habitat in parts of South and Western Australia.

Sesuvium portulacastrum (Aizoaceae) was an unexpected find during our September visit to the Bushland Beach Channel Naturalisation Project. It is the first saltmarsh species in our Plant of the Month series.

Sesuvium portulacastrum is a sprawling perennial plant, green and succulent (above) during the wet season, turning reddish (below) during extended dry periods.

Sesuvium portulacastrum is commonly called Sea Purslane, although the same name is also used for several separate species.

Sesuvium portulacastrum produces small pink or mauve flowers for much of the year. They can be easily missed as they open for only a few hours each day. The flowers are followed by small round seed capsules containing tiny black seeds.

Fast growing Sesuvium portulacastrum forms a dense mat, providing natural erosion resistance near the shoreline. For the same reason it can be useful for coastal revegetation programs.

In some countries, Sesuvium portulacastrum is harvested from the wild and used as a vegetable or condiment, appreciated for its salty flavour and crunchy texture.

In cultivation Sesuvium portulacastrum could serve as a hardy ground cover in full sun and well-drained sandy soil. It can be easily propagated from seed or rooted stem cuttings.

Drosera finlaysoniana (Droseraceae) was just one of many species we found in flower during our recent outing to White Mountains National Park, but it was a bonus for the Editor who is a long-term Drosera enthusiast.

Unlike compact Drosera species with their leaves arranged in a rosette close to the ground, Drosera finlaysoniana is a slender upright plant with long narrow leaves reaching out like octopus arms.

Drosera finlaysoniana leaves are covered in glistening sticky tentacles that reflect sunlight beautifully, inspiring the common name ‘Sundew’ for these and other Drosera species. More importantly for the plants, their sticky tentacles trap unwary insects (photo above). Then the leaves secrete enzymes to digest the insect bodies, providing extra nutrients that allow these so-called ‘carnivorous’ plants to thrive in very low fertility soil.

Drosera finlaysoniana is “tall” compared to compact rosette Drosera species but still a small plant with a central stem typically less than 50 cm. It tends to sprawl sideways among other herbs and grasses (photo above) so it can be quite difficult to spot.

There’s further difficulty, because Drosera finlaysoniana can easily be confused with some other octopus-arm Drosera species (section Arachnopus in botanical taxonomy).

In the photo above, Drosera finlaysoniana and Drosera serpens are growing side-by-side, but who noticed?

Their flowers look similar and can be pink or white in both species, so flowers don’t help with identification. Instead, look at the base of the leaves, marked with red arrows in the photo above. This is where botanists would look for the petiole. The leaves of Drosera finlaysoniana (A) have tentacles extending all the way to the junction with the main stem. In contrast, Drosera serpens (B) has distinct tentacle-free petioles.

Melhania oblongifolia (Malvaceae) got the Editor’s vote as the prettiest small flowering plant spotted on our recent outing to the Mingela Range. From late morning onward its brilliant flowers were displayed to full advantage (photo above) after unfurling very slowly earlier in the day.

Melhania oblongifolia is a small understorey plant adapted to open woodland, monsoon forest and vine thickets. Its natural range extends from east to west across most of northern Australia. In our region it can be seen near the coast (photo above Cape Pallarenda) and in dryer inland areas (photo below Mingela Range).

Melhania oblongifolia is not well known in cultivation but some of our members have grown it and found it a very attractive and hardy addition to their gardens (photo below) provided it has good drainage.

In the wild, we usually see Melhania oblongifolia growing fully exposed to the sun. Nevertheless, in gardens of our members, it has grown well and flowered well in light shade as well as in full sun. Occasional light pruning has been helpful to encourage bushier growth and more flowers (photo above).

Individual flowers are short-lived but each stem produces multiple buds (photo above) and conveniently, Melhania oblongifolia tends to flower intermittently almost all year round in favourable growing conditions. When the seed cases split open (photo below), it is easy to collect seed and propagate new plants.

Many native plant enthusiasts will readily identify the tall trees in the above photo as Paperbarks, but can you say exactly which species? If you’re unsure, you are with the majority.

On a recent outing, we learned from expert botanist Russell Cumming that these trees are Melaleuca aff. viridiflora (Myrtaceae), actually a new species hiding in plain sight!

As indicated by “aff.” in the botanical name, these trees are similar to, but distinct from the well established species Melaleauca viridiflora. Russell pointed out, recognition as a separate species is justified by consistent points of difference including smaller, greener leaves and whiter flowers (photo above) and a different flowering time.

In comparison to M. viridiflora, Melaleuca aff. viridiflora grows into a larger tree and prefers swampier habitats (photo above). Surprisingly, it has not yet been formally described although it is widespread and abundant, occuring from central QLD to Kakadu.

To fully appreciate all the differences between the two species, you need to see live specimens. However, flower differences are apparent in the following photos. The whiter flowers of Melaleuca aff. viridiflora are shown above, and below are the creamy-green flowers of Melaleuca viridiflora

There is also a very attractive but less common form of Melaleuca viridiflora that bears reddish flowers, photo below.