Stylidium piliferum - Common Butterfly Triggerplant

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Stylidium piliferum - Common Butterfly Triggerplant

As its name suggests it is a common plant southwest of a line from the north of Perth to Israelite Bay. Locally it favours deep non-calcareous sandy soil, but is also known from granite and gravel areas. It is found in heath and open woodland, especially in clearings, along tracks and after low intensity bushfires.

Interestingly, there is another very similar Stylidium that can on occasion be found growing nearby. These species are separated by habitat, S. piliferum prefers the well-drained sandy soils, whilst the other, Stylidium corymbosum var. corymbosum, occurs on the floodplains and around swamps, where in dark peaty soils they can after rain, be inundated for several days at a time during the winter/spring period.

Besides the marked differences of habitat, they differ most obviously by the flower arrangement, with S. piliferum having a loose raceme (stalked single flowers, branching individually from the flowering stem), whilst the flowers of S. corymbosum form in compact clusters (head or corymb). However, they are easily confused in the bush, particularly when they may be growing only 30 metres/yards apart. Stylidium corymbosum var. corymbosum has also been detailed in this blog and can be found listed in the right-hand column under ‘Species List S.”

Locally, Stylidium piliferum is usually less than 25 cm (10”) in height, but may grow to twice that in overgrown conditions. The white/cream/yellow flowers bloom prolifically from September to November, after which time the leafy rosette will die back to the rootstock, where in spring the plant will reappear again.

The trigger (stylar column), which is adapted to carry the equivalent of both the stigma and anthers, is activated when a flying insect lands on the flower and trips the mechanism to release the trigger, which quickly swings up between the larger petals to dab pollen on the insects back (see fly photo above). To enable cross pollination, the trigger resets itself to await another insect, and after all the pollen has been distributed, the stigma organ becomes active to receive pollen from other flowers, carried to it by other insects.

Stylidium is part of the Stylidiaceae (Triggerplant) family.

Stylidium turleyae – Turley’s Stylidium

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Stylidium turleyae – Turley’s Stylidium

There are some plants, which are so common and widespread that you expect them to be published and the details readily available, well Stylidium turleyae is such a plant except there is no key to it that I have found, plus the journal in which it is published is not well known. The result has been many hours of research to track it down.

I can remember the first time I encountered this plant, it was over twenty years ago to the NE of Mt Heywood (80 km NE of Esperance). For a few years beforehand I had been surveying this mallee region and knew it well, then a large bushfire passed through and what I had known was no more. However a completely different suite of native vegetation not seen before made an appearance, of which Stylidium turleyae was one of them.

This species was extremely common in sandy loam soils over a wide area and were literally in their millions, yet I had not seen one before the fire. They remained around for 2-3 years, then started to disappear as larger vegetation began to establish themselves to deprive the Stylidium of light and moisture. Some plants remained for several years after the fire, but only in scattered small colonies and individuals that were either growing along the bush track or in a natural clearing.

At the time of this post-fire discovery, I assumed it would be well known and its details published, but I could not locate it in any of the botanical publications available at the time. So I sent a couple of specimens to the herbarium, but heard no more. Since then I have encountered Stylidium turleyae on many occasions, but still I could not pin a name on it. This made me so determined to find it that I recently researched all the taxonomic botanical information concerning this genus available from the WA Herbarium, but still had no success.

In utter desperation I started viewing each of the hundreds of species detailed by the herbarium; I started at (a) and it was not until (t) that I eventually found it. Unfortunately other than the actual FloraBase species listing, there appears to be no other reference to help locate it, which means you must know its name in order to find it, therefore a Catch 22 situation. Stylidium turleyae was published in the WA Naturalist in 2004 (WA Field Naturalist Club), which has a limited botanical circulation and of which I am not included.

Anyway after all of the above, I am pleased to have eventually located it, as it has been an irritation to me for a considerable period of time. The plant as I have mentioned, is very common (for a few years) after fire and distributed from Lake Grace (west of Esperance) to Israelite Bay (east of Esperance), where it favours the inland mallee region, although it can also be found nearer the coast in non-calcareous soils. It mainly flowers (pink or white/pink) in September and October, but with good rainfall can also flower as late as December. In hot weather the foliage dies back to the rootstock to regrow when conditions improve.

Stylidium turleyae is named after Coral Turley, an active member of the Esperance Wildflower Society (no connection to me or the Esperance Wildflowers Blog).

Stylidium is the major genus of the Stylidiaceae family.

Stylidium rupestre - Rock Triggerplant

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Stylidium rupestre - Rock Triggerplant

This species is a low clumping plant, seldom exceeding 30 cm (12”) in height (but known to reach twice that size) and although called the Rock Triggerplant, does not always grow on rocks. It can however also be found in sheltered, moist sandy soils usually within 2 km (mile) from an outcrop, where the acid soils in these places are derived from the more elevated rocky sites. On large granite outcrops, it may be encountered growing on rubble in dappled sunlight produced by taller vegetation along drainage gullies.

The sheltered moist and draining soils required by Stylidium rupestre, mean it is largely a near coastal species of the higher rainfall zone between the Stirling Range (near Albany) to Israelite Bay (east of Esperance). As the plant spreads it produces stolons (ariel roots) that permits it to either extend its range vegetatively or via seed, but owing to limited habitat, colonies tend to be restricted to relatively small areas.

Stylidium rupestre has in the past been known by several varieties, but these have now been discontinued and it is now only known by the species name above. It is reasonably easy to identify, by its distribution and habitat, the stoloniferous habit, glandular hairy spatulate (spoon-shaped) leaves, plus the 1-8 creamy yellow racemose flowers. Flowering is quite lengthy, occurring between September and December.

The genus Stylidium belongs to the Stylidiaceae family.

Stylidium corymbosum var. corymbosum – Whitecaps

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Stylidium corymbosum var. corymbosum – Whitecaps

This attractive Trigger-plant is very common in coastal and near coastal locations between Albany and 70 km (45 miles) east of Esperance. It is found in non-calcareous, moist sand/peat soils in low-lying areas (often winter-wet) like swamps and flood plains, or where there is seepage.

Stylidium corymbosum grows compact leafy rosettes to 4 cm (1.5”) diameter, which can develop off-shoots to form clumpy green cushions (red if ground still wet) around 15 cm (6”) or more in length and width. These clumps made of many individual rosettes, each produce flowering stems 10-12 cm (4”- 5”) in height, which carry many white flowers over several weeks.

There are two varieties of Stylidium corymbosum, the other is var. proliferum that only occurs around Albany, so locally cannot be confused with var. corymbosum. They differ by var. proliferum having broader petals and largely reproducing by producing more widely spaced and less compact off-shoots.

Locally A very similar species Stylidium piliferum, the Common Butterfly Trigger Plant can be easily confused, as it also grows in a heathland environment at the same time (October and November), plus is a more widespread species. However, they do not grow together as Stylidium piliferum prefers better drained soils, so will be found on higher ground, often surrounding the swamps and moist flats where Stylidium corymbosum occurs.

Besides the very different habitats, these similar looking species can be distinguished by the foliage, with S. piliferum having much longer hairs on the leaf tips, plus ragged transparent leaf edges (smooth on S. corymbosum leaves). The S. piliferum flowers are arranged in panicles (branched, uneven clusters), whist S. corymbosum as its name suggests are arranged in corymbs (flowers developing to a similar level, by the lower flower stalks growing longer than the upper ones).

The Stylidium genus belongs to the Stylidiaceae family.

Stylidium calcaratum - Book Trigger Plant

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Stylidium calcaratum - Book Trigger Plant

An extremely common little plant, often occurring in their tens of thousands, if not millions. However it is often overlooked as the top and bottom pair of petals fold together (book-like) and being small (usually under 10 cm or 4” in height), plus having white petals in reverse, make it look like a finished flower. However if seen in the morning when pleasantly warm and sunny, there will be a mass display of pretty colourful flowers.

Stylidium calcaratum is an annual herb, reproducing from seed every year and growing in moist peat/sand soil around swamps, rocky outcrops, seepage areas and floodplains. It does not grow in wet or very dry soils, but in low-lying flat areas where the soil remains reasonably moist. It can be seen from the photographs that petal colour can vary considerably, although their markings tend to be consistent.

The feature that makes these plants quite distinctive and as their Latin species name suggests, ‘calcaratum’ means spurred and refers to the usually long nectary spur at the rear of the flower. Sometimes this appears to be lacking, but will only be seen when its protecting calyx lobe is lowered at maturity. It also has 2 small appendages in the throat.

The only other Stylidium species it could be confused with is S. ecorne, once classified as a variety of Stylidium calcaratum. It differs by having a much smaller spur, or none at all, plus the upper petals instead of being tri-lobed are single acutely lobed; also despite being coastal south of Perth, is more of a wide ranging inland species, especially around granite outcrops. Stylidium calcaratum on the other-hand is generally near coastal particularly in the southwest, but also extending north to Eneabba and east of Esperance to Cape Arid.

Flowering is recorded from July to January, but this is very dependent on local rainfall, as they will quickly disappear upon the onset of hot dry weather.

The Stylidium genus is part of the Stylidiaceae family.

Stylidium preissii - Lizard Trigger Plant

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Stylidium preissii - Lizard Trigger Plant

This small plant with appressed scale-like leaves, grows in deep sandy non-calcareous soil on elevated hillsides where other vegetation due to the dry environment is usually lower and more spaced, thereby leaving open areas for small plants like this species to colonise.

The Lizard Trigger Plant spreads in a rambling manner and seldom exceeds 15 cm (6”) in height, often with its lower branches buried in the loose sand where they commonly take root. The tightly appressed and overlapping leaves are neatly arranged around the stem and highlighted by their broad semi-transparent margins.

The terminal flowers vary from pink to white and produced towards the end of the year (October to December) when it is beginning to warm and most other Stylidium species have ceased to bloom. Stylidium preissii although not forming large colonies, can be collectively common as scattered individuals and small groups throughout its habitat.

This trigger plant ranges over coastal and near coastal regions from Albany to east of Esperance (to Israelite Bay), plus is also recorded around Perth although less common.

Stylidium is the dominant genus of the Stylidiaceae family.