Last week, Alister and I returned from a month-long holiday spent wildlife-watching in Namibia, hence my lack of recent posts. Any time I currently have free is consumed by desperate attempts to wrangle the jungle of weeds that sprung up while we were away. Consequently, I don’t have much to report in the way of recent local wildlife sightings, but I did want to share some news about a couple of local, threatened plant species that call the Pine Mountain area home.

Most of the plants I feature on this blog grow in the vine-scrubs that cover the northern half of the suburb of Pine Mountain. However, the Spotted Gum/Ironbark forests that grow on the sandstone-derived soils in the southern part of the suburb, and in the neighbouring Muirlea and Chuwar, support a vastly different plant community. Last month, Lockyer-based plant enthusiast and vine-scrub aficionado, Martin Bennett, alerted me to a small population of the threatened shrub Sophora fraseri he recently found growing along a powerline easement in Spotted Gum/Ironbark forest beside the Kholo Gardens. I had visited the site briefly several years ago, but clearly hadn’t ventured far enough in to see this plant. I finally found some time today to go and check them out. To my excitement, I not only found the Sophora, but I also encountered a second threatened plant species, one that I had been keeping an eye out for some time: Calyptochloa gracillima subsp. ipsviciensis. I thought it was worthwhile devoting a little blog real estate to these two special local plant species.

The “Brush Sophora”

Sophora fraseri often goes by the common name of “Brush Sophora”, on account of it being an inhabitant of the “brushes” (an old term for rainforests and vine-scrubs), as opposed to the coastal dunes inhabited by the other Sophora species native to Queensland. The common name is a little misleading, though, as it doesn’t tend to grow within intact rainforest. Rather, it favours the sunny rainforest edges and gaps, and ecotonal areas where vine-scrubs transition into eucalypt forests. I had only previously found one individual in Pine Mountain, which was growing in a small, grassy clearing in a remote part of Cameron’s Scrub. The population found by Martin was also growing in a highly disturbed environment, along the edge of a slashed track beneath powerlines. I found nine individuals separated by less than 50 m. The location where they were growing was dominated by Narrow-leaved Ironbarks (Eucalyptus crebra), but there was a strong vine-scrub component to the midstorey, which is precisely the type of ecotonal environment the species favours. I didn’t observe any within the surrounding Spotted Gum/Ironbark Forest where vine-scrub species were absent. They evidently can’t grow (or compete) on the dry, infertile, sandy soils that support Spotted Gum/Ironbark forest. Rather, they are confined to soils with a greater proportion of clay, where other rainforest species (e.g., Pittosporum viscidum, Alyxia ruscifolia, Flindersia collina, Cupaniopsis parvifolia and Excoecaria dallachyana) also colonise in the absence of regular fire.

Both the Queensland and Australian Governments list Sophora fraseri as a vulnerable species. Being confined to southeast Queensland and northeast New South Wales (the part of Australia with the fastest growing human population), its habitat is under heavy threat from clearing. Luckily, many remaining populations of Sophora fraseri, including the two I know of in Pine Mountain, occur in council reserves, national parks or other protected areas. Instead, weeds probably pose the most immediate threat to the species. Habitats favoured by Brush Sophora (sunny, disturbed sites on better quality soils) are precisely the sort of environment where weeds thrive. The small stature of Brush Sophora (it rarely grows much taller than 1 m) means that it is easily smothered by Lantana (Lantana camara), Ochna (Ochna serrulata), Climbing Asparagus (Asparagus africanus) and Green Panic (Megathyrsus maximus), all of which were observed invading the population near the Kholo Gardens. It is doubtful whether the local populations of Brush Sophora will survive these weed invasions without regular intervention from humans, in the form of weed control. Fortunately, a large number of Lantana clumps in the vicinity of the Brush Sophora population had been recently poisoned when I visited, so hopefully Ipswich City Council or Energex (I’m not aware of who was responsible for these weed control works) continues their efforts.

Brush Sophora makes a great addition to vine-scrub plantings. They are easy to propagate from seed, which germinates relatively quickly. Being a legume, they also fix nitrogen in their roots, helping to improve soil fertility in depleted soils cleared of original vegetation. They are relatively tolerant of dry sites yet can withstand short-term waterlogging. They do prefer (and look best with) plenty of sun, but cope well with half shade. I have even noticed self-sown seeds germinating at home in the relatively heavy shade beneath adult plants. Young seedlings do not, however, appear to cope with heavy leaf litter fall, which smothers them and prevents establishment within intact rainforest. They would make an attractive addition to most suburban gardens, as they usually start flowering in the first year after planting. However, I find individual plants sometimes die back to the ground in response to drought or insect attack. They normally re-sprout from the base once conditions improve.

_{Sophora fraseri was covered in showy, yellow pea flowers in late September. These photos are all taken of planted specimens at home.}

Calyptochloa gracillima subsp. ipsviciensis

Calyptochloa gracillima subsp. ipsviciensis is a mat-forming grass that was only discovered in 2011 and scientifically described in 2012. Neither it nor its close relatives have a common name, but given how cumbersome its scientific name is to write and say, I’ll refer to it as the Ipswich Carpet Grass for simplicity. Both the Australian and Queensland Governments list it as critically endangered, the highest threat level that can be awarded to any species. This is primarily because it is known to occur at only a handful of locations, all of which are close to the urban centre of Ipswich. It is therefore at high risk of habitat loss and weed invasion.

The Ipswich Carpet Grass superficially resembles a couple of other species of mat-forming grasses (Ottochloa gracillima and Oplismenus aemulus) that I described in my previous post about the grasses of local vine-scrubs. However, it can be easily distinguished by a combination of very hairy leaves, unbranched flower spikes and habitat. All our other mat-forming grasses are confined to the damp, shady understorey of vine-scrubs, whereas Ipswich Carpet Grass inhabits dry, shallow soils beneath Spotted Gums (Corymbia citriodora) and Narrow-leaved Ironbarks (Eucalyptus crebra). Even within this environment, Ipswich Carpet Grass appears to occupy a very specific niche that few other species can tolerate. It occurs almost exclusively in the partial shade beneath wattles and ironbarks, trees that are notorious for being aggressive competitors for soil moisture (as many Australian gardeners can attest). In sunnier or damper locations, this low-growing grass is outcompeted by taller native and exotic species.

Ipswich Carpet Grass is a species I had been meaning to search for for many years. I knew the type specimen was collected near the Kholo Bridge but my time-poor schedule coupled with my previously mentioned antipathy towards grasses, meant I hadn’t made the effort to go in search for it. Still, I have always kept an eye out for it whenever I found myself in potentially suitable habitat. Such was the case today, when I went in search for the Brush Sophora. The track to the Brush Sophora passes through the sort of Spotted Gum/Ironbark forest that is typical along the southern end of Riverside Drive. Even though I knew this was possible habitat (and close to the type locality), the forest here is heavily invaded by weedy grasses, so I didn’t have high hopes of encountering the Ipswich Carpet Grass. Yet, to my amazement, this critically endangered species was one of the dominant ground covers present. The large, lime-green mats that it formed stood out from the browns and olive greens of the other grasses, which were evidently suffering more from the dry month we have just experienced. I don’t know whether such a large population of this grass has always been at this site, or whether the wet year we’ve just experienced has been especially favourable for its spread.

The harsh environment in which the Ipswich Carpet Grass grows appears to afford some protection against weed invasion. The weeds most abundant on the poor sandy soils in ironbark forests (e.g., Red Natal Grass and Signal Grass) don’t appear to withstand the heavy root competition beneath wattles. As a result, there tended to be a sharp demarcation between the mats of Ipswich Carpet Grass beneath trees and the dense cover of weed grass in the gaps between trees. However, there are a handful of particularly tough weeds that can colonise dry, shady sites, and two such species (Mother-of-Millions Kalanchoe delagoense and Creeping Lantana Lantana montevidensis) were invading some of the patches of Ipswich Carpet Grass. If this threatened species is to be saved from extinction, a weed control program is likely to be required.

Apart from weeds, the other main threat to the Ipswich Carpet Grass is actually ignorance. Despite this plant occurring nowhere else in the world except for within Ipswich (it will soon be the only taxon endemic to the city, after recent research has revealed Notelaea ipsvicensis to be an invalid species), the Ipswich City Council does not currently list it among its species of significant flora and fauna. Without a spotlight on its plight, a small native grass such as this will inevitably be overlooked. This is clearly already happening at the Brush Sophora site, as quite a few of the patches of this critically endangered grass had been accidentally killed through contact with the broad-spectrum herbicide that had been used to control Lantana camara. Normally a little collateral damage to native grass is a small price to pay for the removal of an invasive weed, but not when that grass is one of the most threatened species of plant in Australia. I have no doubt that the well-meaning weeders had no idea they were in the presence of a critically endangered species. Otherwise, a more appropriate broad-leaf herbicide (which doesn’t kill grasses) would have been applied to the lantana instead.

I have never tried to propagate or grow Ipswich Carpet Grass as it is doubtfully native to the vine-scrubs that grow on our property. I imagine propagation would be very easy from runners, as it is for most stoloniferous grasses. I also imagine that this would be a tough species in gardens that could become quite rampant in the absence of competition with other species. Still, it wouldn’t be a disaster if one of Australia’s most threatened species of plants becomes a little weed-like in gardens!

Keep an eye out for this species whenever you are in drier eucalypt forests in western Brisbane, the Lockyer Valley, Somerset or elsewhere in southeastern Queensland. I strongly suspect it is a species that will turn out to be more widespread than currently recognised…if only I and all other native plant enthusiasts would stop ignoring the grasses when out in the bush!