Olax phyllanthi - Olacaceae

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Olax phyllanthi - Olacaceae

The genus Olax belongs to the very diverse Olacaceae family that is widely distributed in the Southern Hemisphere. These plants are to various degree root parasites on other species, although a group within the family are not, but based on floral parts still belong here. Olax are partially parasitic (hemiparasitic) and dependant on the host plants ability to produce moisture and nutriments, will determine the extent these hemiparasitic species are dependent upon them.

In Western Australia there are 6 Olax species, with 2 found in the Esperance region and both are easily confused. Olax phyllanthi is mainly encountered on stabilised tertiary calcareous dunes, where it is quite common and widely spread from Israelite Bay (east of Esperance) along the coast to Augusta (most westerly portion of the south coast). In this habitat they will occupy hollows and dune slopes and due to their contrasting pale grey/green color can be seen and recognised from some distance.

The other local Olax (Olax benthamiana) can also be found in the calcareous dunes region, but is more widespread further inland on sandy soils, sometimes over gravel. The most obvious difference between them are the leaves, which are channelled with O. benthamiana and not flat like Olax phyllanthi, plus the tips of the former are usually pointed and recurved. The flowers of both species have stamens and staminodes (rudimentary sterile stamens), which are forked with O. benthamiana, but undivided with O. phyllanthi.

The flowers of Olax phyllanthi can bloom on and off throughout the year, but are not much to look at, being solitary, white and small. However the weeping grey/green foliage with the distinctive broad oval leaves are certainly eye-catching and further enhanced as they sway heavily in the wind. In sheltered hollows shrubs can grow to 1.5 metres (5’), but on exposed slopes are usually less than a metre (3’) in height.

Chamaescilla corymbosa var. corymbosa - Blue Squill

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Chamaescilla corymbosa var. corymbosa - Blue Squill

The genus Chamaescilla in Western Australia now belongs to the Asparagaceae family, but it has been moved around quite a bit recently and the question as to exactly where it should be placed still has a question mark with some authorities. Some retain it in Liliaceae, although Laxmanniaceae and Anthericaceae are also used, but as the WA Herbarium have placed it under Asparagaceae, so shall I.

Chamaescilla corymbosa var. corymbosa is an ephemeral herb, growing from a tuber to produce a rosette of linear leaves and flowering (depending on moisture availability) between July and December. It then dies back to the tuber to appear again the following year. Aborigines would eat the tubers (about the size of a child’s little finger) that are easily gathered with a digging stick as they are often numerous and near the surface. The ones I have sampled (after the plant has died back to the tuber) had a starchy flavour a little like a potato and are pleasantly crunchy.

Flowers are mostly blue, although they grade from a deep to a pale blue and even white. They are extremely common and widespread in sandy soils, which can be over gravel or granite or with a peat content in low-lying areas and subject to heavy rainfall flooding. They range in WA from Israelite Bay (east of Esperance) around the coast and through the wheatbelt to Kalbarri (around 500 km or 300 miles north of Perth); it also extends across the southern part of Australia (excluding the dry Nullarbor and western SA) to Victoria and Tasmania.

These herbs range inland to the mallee region, but only where there are sandy loam soils and if these overlie clay/gravel, the Blue Squill plants are likely to be much larger, growing to over 30 cm (12”) in height, whereas in deep sand they are usually less than half that, which probably indicates a higher level of soil nutrients. Like most small plants they greatly benefit from the interaction of bushfires that reduce competition from shrubs, plus the fertilising wood-ash will encourage their flowering to produce blue floral carpets in some habitats.

Xanthorrhoea platyphylla - Grasstree

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Xanthorrhoea platyphylla - Grasstree

Xanthorrhoeaceae is the family of grasstrees with many species spread around much of Australia including the dry centre. Not so many years ago there were a number of other genera included, but these have progressively been allotted to other families, so now Xanthorrhoeaceae has only the Xanthorrhoea genus. Grasstrees are also known as Blackboys or Yuccas and currently in Western Australia there are 9 described species and another yet to be. However as these plants are very bulky to collect, it takes a very dedicated botanist to gather more than is absolutely necessarily, consequently there are a number of gaps in herbarium collections, including from the Esperance district.

There is only one grasstree recorded for the Esperance region, but another species exists around 90 km (56 miles) west of Esperance, notably along the Munglinup Farmers Road that is more robust and noticeably different in many respects. So it is either a known species a long way from its recorded distribution, or is undescribed. However, apart from that species, Xanthorrhoea platyphylla is common and widespread in coastal and near coastal environments from Israelite Bay to Albany.

The trunk of Xanthorrhoea platyphylla can reach 3 metres (10’) in height with a single trunk, or with one or more branches. These are made from their leaf bases that pack down to form a thick 5 cm (2”) or more covering of the living pithy centre. This is a slow process and larger plants are probably several hundred years of age. This leaf base compaction rate is highly variable and dependant on the habitat (nutrition and moisture availability), the frequency of bushfires as these encourage considerably more foliage growth compared to those not burnt for many years, so gauging the age of grasstrees by their height is most unreliable.

Xanthorrhoea platyphylla prefers growing in a sandy soil, which may be deep, or shallow over granite or gravel. The pH of the sand can be acid or alkaline, although the latter are mainly confined to the hollows between tall-stabilised dunes, whereas with acid soils they will happily grow on the top of sandy hills. They will also grow in low-lying areas subject to temporary flooding, so as can be gathered growth rates vary enormously.

Unfortunately, many grasstrees particularly in the lower areas and where soils are acid, are dying from the effects of dieback (Phytophthora cinnamomi) a disease that rots their roots. In fact the number of dead and dying grasstrees is a very good indication of the presence of this disease.

Aborigines found many uses for this plant, from eating the growing pithy centre or bardi grubs (moth and beetle larvae) from dead plants, to using the resin as a heavy-duty adhesive, especially for tool making. The resin as can be seen above, becomes semi-liquid or highly malleable when heated, but sets rock hard when left to cool. The resin is readily available and can be seen on burnt trunks or as globules on the ground. It forms around the base of the leaves to be melted in bushfires, which afterwards will set hard and provide strength and rigidity to the trunk.

Despite its slow growth between bushfires, it can develop remarkably quickly once one has passed and good rain has fallen. In these circumstances it springs into action with new foliage growth and flower spikes over two metres (6’-7’) in height and all within a matter months, thereby completing its reproductive cycle long before other plants that need to reproduce from seed get past the germination stage.

Rarely does Xanthorrhoea platyphylla flower without the influence of fire, but sometimes odd ones will, particularly after a hot summer and/or growing in an open position, but after a fire they mostly all bloom, so around Esperance, flowering can be anytime between June and January.

Macrozamia dyeri - Zamia Palm

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Macrozamia dyeri – Zamia Palm

Most would know what a Cycad was, probably coupled with images of Dinosaurs munching on them as are commonly drawn to illustrate an ancient world. Although the large dinosaurs have long gone, cycads are still doing very well and are distributed over much of the warmer parts of the globe. The genus Macrozamia is one of several in the family Zamiaceae, and from which the common name of Zamia Palm originates. In Western Australia we have 3 Macrozamia species, but only Macrozamia dyeri is found in the Esperance district, the other two are along the west coast in the Perth region.

Macrozamia dyeri is recorded as mainly growing in deep white calcareous sand, but this seems to be something that has been passed down scientific literature from early times, as from my experience this is not a preferred habitat although they can sometimes be found there. They are also found on deep non-calcareous sand, but favour sand over granite and are often very common around low-lying outcrops, plus the deeper soils on larger mounts. Most of the white sand in the Esperance region (can extend right down to the beach) is actually acid, having been leached of alkaline material in bygone days when rainfall was much higher and large floodplains drained into the sea. The alkaline zone (when it does exist), is usually within 3 km of the sea, so is not overly plentiful and has only a limited number of species when compared with other habitat zones. Even when there is limestone, it does not mean the topsoil is calcareous as this too may have either been leached of alkaline materials, or eroded away and been replaced by non-calcareous windblown sand.

The palm-like Macrozamia dyeri, develops a trunk from the accumulation of leaf bases in a similar way grasstrees do (Xanthorrhoea spp.) and is consequently very slow growing. As the trunks can grow to 3 metres (10’) in height (mostly less than half that size), some plants are obviously hundreds of years old. They are nevertheless impressive plants with arching fronds in excess of 2 metres (7’) to provide a wide canopy. Fire is required for the plants to flower and the trunks are usually black because of it, but like grasstrees, they suffer no ill effect regardless of how often they are burnt.

There are male and female plants whose flowers are wind pollinated (those shown above are male, the female ones are similar but more chunky), the seeds when produced are the size of a large raw date and occur in considerable quantity. The seed is surrounded by a thin shell containing a nut-like interior and is obviously an excellent food source, but these ancient plants have developed defences against being eaten and are highly poisonous as early explorers and settlers quickly discovered, when they doubled up in pain after eating them, some even dying. However aborigines over thousands of years of occupation discovered ways to neutralise them by roasting, leaching and aging, etc (don’t try this at home), so to them it became an important food source. With their fire-stick land management, it is quite likely they farmed these plants by burning regularly to encourage flowering.

Macrozamia dyeri is a near coastal species and does not extend into the inland mallee region (approximately 50 km or 30 miles from the coast), probably because of non-sandy soils, as heat and prolonged dry periods do not trouble these plants. They range from near Cape Arid (110 km or 70 miles east of Esperance) to the Salvation Boat Harbour region, a similar distance to the west of Esperance. As they rarely flower without the influence of bushfires, they will usually do so in the spring of the fire year, or the following year.

Halgania andromedifolia - Blue Bush

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Halgania andromedifolia - Blue Bush

Halgania andromedifolia is a reasonably common and widespread shrub, particularly of the mallee region that typically has a fine sand/clay topsoil over limestone, although it can also be found on gravel and over granite, although the latter usually has a limestone overlay. It does very well after bushfires that reduces competition from other plants, especially overhead eucalypts that dominate available moisture and sunlight in a low rainfall district.

Shrubs in the Halgania genus are generally known as Blue Bushes as most have deep blue flowers, although purple, pale blue and even white forms are not unknown. The 1.5 cm (½”) diameter flowers of Halgania andromedifolia are almost a royal blue and as they grow in terminal clusters can be very showy. The leaves are a shiny bright green and quite viscid (sticky), which provides a gloss.

There are 14 West Australian Halgania species, with 4 being recorded for the Esperance region, most occur inland and only one is commonly found near the coast. It is interesting to note that hardly any collections have been made SW of a line drawn between Albany and Perth, where conditions during winter are colder/wetter and although containing coastal heath, is otherwise heavily forested.

Halgania andromedifolia grows mostly from ½ to 1 metre in height, slightly wider than high and usually bushy from the ground up. Flowers are recorded from August to January, but this would depend on seasonal rainfall, which can be quite variable in these drier areas. Flying insects (due to the sticky foliage), I imagine would be the main pollinators.

Billardiera coriacea – Pittosporaceae

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Billardiera coriacea – Pittosporaceae

The Pittosporaceae family has quite a range of shrubs plus the odd tree, but is noted for the number of climbers and twiners, many with impressive floral displays and most occurring in Western Australia. In Billardiera there are 10 WA species and all are either climbers or twining shrubs, they range from the Nullarbor to near Geraldton on the west coast, but are particularly widespread around coastal regions and the Wheatbelt.

Billardiera coriacea will climb on shrubs to 1.5 metres (5’), but is easily overlooked despite having broad foliage and bright flowers. It blends well into its supporting shrub, seldom exceeding its foliage, but filling gaps between  stems and generally bridging holes. It is not that it is well camouflaged, but you need to look directly at the shrub to spot it, which may be one in hundreds. Billardiera coriacea is sparsely recorded from near Israelite Bay (east of Esperance) to Walpole (west of Albany), then north (mainly through the inland Wheatbelt) to near Geraldton (north of Perth). However it is probably more common than collections would indicate, but overlooked.

The flowers of Billardiera coriacea are up to 2 cm (3/4”) in length and are initially cream with the petals forming a tube, but as it matures it changes to pink, then to purple, plus the petals separate to reveal the developing berry fruit. Locally it occurs in deep non-calcareous sand, but can also be found over gravel or clay, providing the drainage is good. It is not overly common, but is quite widespread, the seed probably spread by birds.

It is recorded flowering from May to November, but if conditions are not too harsh and it has access to moisture or shade, will also bloom during summer.

Stachystemon brachyphyllus and S. polyandrus Intermediate

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Stachystemon brachyphyllus and S. polyandrus Intermediate

Stachystemon is a member of the highly diverse Euphorbiaceae family and is distinguished from other genera by the perianth (calyx-like) around individual flowers and the two lobed stigma of female flowers. Both Stachystemon brachyphyllus and S. polyandrus are recorded for the east of Esperance where the above colony was discovered in the second year after a bushfire. However it is not clear if these particular plants are a hybrid between the two, or a transition form as one species evolves to the other, as both appear closely related. I include it here as it is of scientific interest, plus also a pretty little shrub.

Stachystemon brachyphyllus is more of an inland species and recorded from the NE of Esperance at Mt. Heywood and Mt. Ragged (50-60 km or around 35 miles from the south coast) in the mallee region. Stachystemon polyandrus is more of a coastal species basically occurring in non-calcareous heathland. This intermediate form was 30 km from the south coast, growing on a north facing sandy slope (probably over gravel, a heavier soil or even granite) and draining to a substantial clay base flooded area. The colony consisted of over 100 plants in about ½ hectare (100 metres x 50 metres).

Stachystemon polyandrus has already been posted here (see right-hand column) and has yellow to white flowers, with male flowers having between 10-14 stamens. Stachystemon brachyphyllus has a reddish flower with around 25 stamens. There are other small differences, but the colour and stamen number are the most obvious. This intermediate form has the reddish flowers of S. brachyphyllus, but the stamen number of S. polyandrus, plus differs in other respects.

In the 2003 paper of David A Halford and Rodney J.F. Henderson of the Queensland Herbarium, titled A revision of Pseudanthus and Stachystemon, from the Studies in Euphorbiaceae series, they do mention intermediate forms between these species, so presumably other colonies also exist. Plants in this colony were all young and not fully grown, so their ultimate height and development could not be obtained, but at this stage were around 30 cm (12”) in height. They were photographed in mid October, so would likely flower between September and December as do S. brachyphyllus and S. polyandrus, with unseasonable weather extending or shortening this period.

Stachystemon polyandrus – Euphorbiaceae

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Stachystemon polyandrus – Euphorbiaceae

Stachystemon polyandrus is a moderately bushy shrub to 90 cm (3’) in height (mostly shorter), with several clusters of yellow male flowers and one or two individual female ones. The female flower can be identified by the single pair of stigmatic lobes (poking above the male flowers), a feature that places this plant into the Stachystemon genus.

In the 2003 revision of this genus by Halford and Henderson, they give the distribution of this species from ‘near Kulin southwards to Fitzgerald River National Park and to Israelite Bay…’ However the WA Herbarium only lists it to the near north and west of Esperance, which also agrees with my findings, so likely the Herbarium do not have any easterly specimens. But whatever the situation, it is certainly more plentiful to the west of Esperance.

These Stachystemon species appear to have at least a partial dependency on bushfire or soil disturbance, as they are nearly always encountered within a few years of such an event, usually in small reasonably compact colonies. This species favours non-calcareous sand over gravel soils and can be found in roadside gravel pits, although you need to walk around as being small leaved and somewhat nondescript, they tend to blend into other vegetation and go unnoticed.

The small female flowers when fertilised will produce a larger conical seed capsule that can be seen in one of the photographs. Like many Euphorbiaceae they will bloom over a considerable period, particularly if weather conditions are not extreme. Stachystemon polyandrus mostly flowers from September to January, but has been recorded at other times too.