This month we put the spotlight on two lovely little plants in the Violaceae botanical family. Pigea enneasperma (photo above) was spotted on our April outing to Bluewater Range, and we found Pigea stellaroides (photo below) a few days later on the rocky slopes near Cape Cleveland.

At a glance the flower shape provides a handy reminder of the common name, Spade Flower. But over recent years, these pretty plants have undergone a pretty confusing series of name changes. Lilac Spade Flower was formally known as Hybanthus enneaspermus and Orange Spade Flower was Hybanthus stellaroides. Then their genus was changed to Afrohybanthus. Now they are Pigea, reverting to the genus that was applied back the 1800s (Forster 2021).

Both of these Spade Flowers are small upright plants with narrow leaves (photo above). Growing as single plants, they are often widely scattered among long grass and other low-growing species so they can be difficult to spot in the wild.

In a garden setting, Spade Flowers provide an attractive display if you establish several plants in a dense cluster (photo above). Tubestock plants are only occasionally available from some native plant nurseries, and nursery-grown Pigea seem to suffer from the inevitable disturbance of being re-planted. Sowing Pigea seed directly in the garden might be the best strategy.

Pigea enneasperma has a wide distribution across eastern and northern Australia (map above left) and also occurs in parts of Asia and Africa. Pigea stellaroides (map above right) occurs in coastal Queensland, New South Wales and PNG.

Spadeflowers have long been used for traditional medical treatments and advanced modern research methods are now being used to study their rare chemical components – read more here.

Millettia pinnata also known as Pongamia pinnata (Fabaceae) is a dry rainforest tree widespread in Queensland and beyond. It has beautiful pea-like flowers (photo above) that appear towards the end of the Dry Season. However, at this time of year, during our Wet Season, it is the tree’s dense green foliage that draws attention (photo below), especially when the leaves are sparkling with raindrops.

The leaves often have numerous small brown patches (photo below) caused by an unnamed leaf miner that Millettia pinnata trees seem to tolerate well. In densely vegetated places, these brown patches can be a useful aid in spotting Millettia pinnata trees from a distance.

In lower rainfall areas like the Townsville region, Millettia pinnata typically grows in riparian forest (along creeks), and in higher rainfall areas it thrives in littoral forest (behind beaches).

Millettia pinnata grows relatively fast, tolerates heat, flooding and extended dry periods, and rarely suffers major insect attack. The species has attracted research attention to investigate its potential for commercial production of biofuel, and several trial plots of Millettia pinnata have been grown in Queensland, Northern Territory and Western Australia over the past decade. We have not heard of any large-scale planting in Australia as yet.

Lophostemon grandiflorus (Myrtaceae) is endemic to Australia, an attractive but often overlooked tree (photo above) that occurs naturally right across the Top End, extending in the east to Central Queensland. It was originally named Tristania grandiflora, then transferred to the genus Lophostemon in the 1980s.

Lophostemon grandiflorus typically grows in well drained native woodland areas near gullies and seasonal creeks. The species evidently benefits from intermittent high soil moisture, and tolerates both temporary inundation and prolonged dry spells. Despite its common names, Northern Swamp Mahogany / Northern Swamp Box, Lophostemon grandiflorus does not normally grow in permanently saturated swamps.

Lophostemon grandiflorus bears clusters of creamy-white flowers edged with brown (photo above). The botanical name ‘Lophostemon’ refers to the tufted clusters of stamens that typify this genus and give the flowers a fluffy appearance when seen from a distance. Close-up, the stamen clusters are visible towards the top and left of the photo above.

Lophostemon grandiflorus trees quite often host epiphytes and mistletoes. In the photo above, there are orange mistletoe flowers partly visible through the Lophostemon grandiflorus foliage. The leaves provide food for native caterpillars including those of the Splendid Ghost Moth and the Rare Red-eye Butterfly.

Lophostemon grandiflorus leaves are mid- to dark-green on their upper surface and pale green on the underside (photo above). There are small oil dots in the leaves although you might need a hand lens to see them.

Saplings and young Lophostemon grandiflorus trees have smooth light brown bark that gradually becomes darker and rougher, almost fibrous, as the tree ages (photo above). The coarse surface and persistent nature of the bark (i.e. not shed seasonally) provides a favourable substrate for mistletoe, orchids and other epiphytes.

In favourable conditions Lophostemon grandiflorus grows readily from seed. One may need patience and good timing to collect seed and it’s worth checking several trees at different locations. They tend to have variable flowering periods and the window for seed collection is brief because the seed capsules quickly swell, open, and shed their contents (photo above).

Cananga odorata (Annonaceae) occurs naturally in Queensland between Torres Strait and the Tully River. It is also native to parts of SE Asia and Near Oceania. Cananga odorata typically grows in lowland rain forest and, under good condtiions, it develops into a substantial tree (photo below).

Although Townsville is south of Cananga odorata’s natural range, specimen trees have grown well Townsville’s botanic gardens and, as we discovered recently, Cananga odorata can also succeed in a home garden. Ishara takes up the story…

“I’ve usually seen Cananga odorata as a large rainforest tree with the canopy high above and with no hopes of seeing or smelling the flowers. So, imagine my surprise while walking down a street in Forrest Beach when a branch filled with fragrant flowers brushed my face.” (photo below)

“Later I revisited this tree together with some NPQ members. Beth with her extensive knowledge explained how the tree was a primitive (old world) tree of the Annonaceae family within the order Magnoliales – in the photo below, note the similar flower structure to magnolias.”

“We noticed some Cananga odorata fruits developing (photo below) and Beth explained that the carpels in the flowers are free and not fused, which gives rise to several fruits forming from a single flower, as opposed to the usual one fruit from one flower in less primitive species.”

Essential oil known as ylang-ylang is extracted from flowers of Cananga odorata and the species is cultivated in plantations for this purpose. Ylang-ylang is one of the most extensively used natural scents in the perfume industry.

A note for gardeners: Regular pruning might be necessary to keep Cananga odorata to a suitable size for a small garden. We noticed the main trunk of that suburban tree appeared to have been broken or cut, possibly to limit its height. This seemed to have promoted branches sprouting from the lower part of the trunk.

This tree caught Pete’s attention during our NPQ May outing but it was mistakenly identified. Later, with Russell’s expert help, it was identified as Corymbia trachyphloia (Myrtaceae).

The trunk of Corymbia trachyphloia has rough bark, tessellated, soft, grey, brown and yellow-grey (first photo below), shedding higher up to leave the upper branches smooth, pale grey to white (second photo below).

The leaves are narrow and lance-shaped, slightly darker green on the upper side (photo below). There were no flowers visible on the tree in May 2023.

Seed capsules that Pete measured were 8 mm long x 5 mm wide, urn-shaped and covered with small pustules.

For more information about this species (and other eucalypts) see
EUCLID https://apps.lucidcentral.org/euclid/text/intro/index.html

During our September outing to White Mountains National Park, a tall single-stemmed shrub caught our attention. It was an intriguing ‘new’ discovery for most of us, identified by the experts in our group as Astrotricha pterocarpa.

We were fortunate that on this occasion we found Astrotricha pterocarpa (Araliaceae) in “full bloom” (photo above) although we needed binoculars to inspect its huge inflorescence high above our heads.

The pale greenish-cream flowers of Astrotricha pterocarpa are covered in fine hairs. The flowers were evidently very attractive to a wide range of insects (photo above).

Astrotricha pterocarpa has large simple leaves (photo above) with a very elongated heart-shape. The leaves are arranged spirally around the upper part of the plant’s un-branching stem. The rest of the stem has conspicuous leaf scars where old leaves have been shed.

Astrotricha pterocarpa is endemic to tropical Queensland with its range extending from south of Pentland to north of Cooktown.