Grevillea prostrata - Pallarup Grevillea

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Grevillea prostrata - Pallarup Grevillea

Grevillea prostrata is a genuine prostrate shrub spreading to over a metre (4’) diameter, and not a form of a more upright species, however there is a difference and that being its pinnate like leaves are held stiffly upright. Although not flexible, they are unarmed and attractively spaced along a prostrate stem that may be completely buried by the sand. The delicate looking pink and white flowers form as rounded clusters and situated at the end of branches.

Most collections of this plant have been made in the Lake Grace region (north of Ravensthorpe), with odd outlaying collections in neighbouring districts including the Frank Hand National Park, which is around 40 km (25 miles) north of where I encountered mine. There is a Pallarup Lake between Lake Grace and Ravensthorpe, which is probably where this species was first discovered and where it gets the common name of the Pallarup Grevillea.

Grevillea prostrata currently has a Priority Four Conservation Code, which means it not currently in need of special protection, but is close to being Vulnerable. In the area south of Lake Tay this species is commonly encountered amongst low heath vegetation on gently sloping sandy hills (sometimes over gravel). Interestingly, the areas that had been burnt (3-5 years ago) had numbers of this species, but in nearby unburnt areas, none were seen. Most plants were juvenile with only a few leaves projecting from the sand that completely covered the stems, this leads me to think that fire kills them and regeneration is from seed.

In the area south of Lake Tay, these plants were common and widespread in habitat, so the species is certainly not rare, although restricted to suitable and often limited habitat. From the plants seen, growth habit was quite open, but I think it would become more branched and compact over time. The leaves stand around 7.5 cm (3”) in height and the flower clusters grow to 2.5 cm (1”) diameter. Flowering is recorded from August to January, but exact timing would very much depend on local weather conditions.

The Grevillea genus is part of the large and diverse Proteaceae family.

Grevillea teretifolia - Round Leaf Grevillea

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Grevillea teretifolia - Round Leaf Grevillea

Grevillea teretifolia is an inland species occurring to the NW of Esperance and spreading north to Kalgoorlie, then west to the Geraldton region and down to the Fitzgerald River National Park (SW of Ravensthorpe). It favours sandy loams over gravel, where it often forms compact colonies in suitable habitat. The closest colony to Esperance that I know is around 110 km (70 miles) northwest of town.

It is a handsome shrub to 2 metres (over 6’) in height, although more commonly half of that size. The foliage is divided, rounded with pronounced ribs and the tips ending in sharp points, whilst the clusters of pink or white flowers dominate the spreading branches.

The flowering period is recorded from June to November, but would probably be influenced by local weather conditions as to when they begin and end. Insects are strongly attracted to the flowers and a variety of colourful beetles, wasps, flies, butterflies, etc, can usually be found feeding from them, making these plants excellent places to check out local invertebrates.

Grevillea didymobotrya subsp. didymobotrya

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Grevillea didymobotrya subsp. didymobotrya

Although this Grevillea is very widespread in the lower arid region of Western Australia, being found to the north of Kalbarri, around Wiluna and east of Kalgoorlie, it only occurs to the NW of Esperance, with the closest colony around 100 km (over 60 miles) away. Here and further NW it favours low lying sandy loams over gravel, where it forms moderately compact colonies that cease once soils deepen and conditions become drier.

The foliage is rounded or slightly flattened and strongly ribbed in cross-section, which gives the initial impression they are tightly recurved. The cream to yellow flowers are mostly terminal and form single or more commonly twinned racemes to over 3 cm (11/4”) in length, a feature the plant is named after. Greek: didymos double, twin + botrys bunch of grapes, the latter referring to the flowers.

This Grevillea has two subspecies, the other being subsp. involuta that is localised to the inland Geraldton region and has obovate to elliptic leaves. Grevillea didymobotrya subsp. didymobotrya can grow to over 3 metres (10') in height, although local plants tend to be around half this size. Flowering time is highly variable, no doubt being very reliant on local weather conditions that favour moist conditions after rain. It is recorded as flowering anytime from June to January, but locally August to November would be more usual.

Grevillea cagiana - Red Toothbrushes

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Grevillea cagiana - Red Toothbrushes

Grevillea cagiana is a large bushy shrub commonly between 3-4 metres (10’-12’) in height, although it can reach 6 metres. The slender upright foliage is a silvery green to 12 cm (4”) in length and in the plants examined was undivided, although elsewhere they may be dissected. The Pink/cream toothbrush flowers with bright orange/red styles, extend from the tips of the upright branches and so are also angled upwards. This results in the styles facing towards the centre of the shrub and not upwards or outwards as most other species, but as the pollinating birds would be perched on the bare inner branches, the flowers are correctly positioned for them.

This Grevillea is mainly distributed in tall mallee heath from the NW and W of Esperance to the Bremer Range, then onto Merredin before turning NE to the Kalgoorlie/ Coolgardie region. It can be quite common in large colonies growing in deep sandy soils (sometimes over gravel), although plants tend to be widely spaced and in the colonies seen, did not form thickets.

The toothbrush flowers with their very bright styles plus slender foliage, immediately reminded me of the much smaller and more coastal Grevillea concinna (Red Combs), but Grevillea cagiana is unlikely to be confused with it, particularly as the similar toothbrush flowers of G. concinna are deflexed. Flowering time is highly variable and can be anytime from June to March, no doubt influenced by local weather conditions in this normally dry region.

Grevillea excelsior - Flame Grevillea

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Grevillea excelsior - Flame Grevillea

The Flame Grevillea like its name suggests is a most impressive looking small tree with vivid orange/red flowers, of which the native honeyeating birds are regular visitors to dine on the floral nectar. The plants I saw in two widely separated colonies, were to 5 metres (16’) in height, but apparently they can grow to 8 metres, plus expand considerably in width.

This remarkable Grevillea is mostly an inland species being mainly found inland from Geraldton to the Kalgoorlie region, then south to near Peak Charles (120 km or 75 miles NNW of Esperance) and only just extending into my Esperance survey district. One of the two colonies seen was a little south of Peak Charles growing in deep sand, whilst the other was growing in gravel off Fields Road around 110 km (70 miles) NW of Esperance and probably represents the extent of its south-eastern distribution. Each colony had between 20-40 plants that were restricted to a few hectares/acres, although 40 km further west they are quite common and widespread. 

Grevillea excelsior was initially confused with a similar species G. eriostachya and sometimes their ranges overlap, but that species seldom exceeds 3 metres (10’) in height and the flowers are usually green and yellow. It is however very widespread and mostly found north of Perth, along the coast to near Broome and inland to central Australia. It is also found in SA and the NT.

The more local Grevillea excelsior (depending on suitable weather conditions) flowers anytime from August to November by producing very colourful toothbrush shaped flowering racemes to 15 cm (6”) in length. The grey/green subpinnatisect foliage is long and slender with lobes to 20 cm (8”) that are only 1.5 mm (less than 1/8”) wide. The lobes are often of different length and not necessarily formed in pairs.

Grevillea anethifolia – Proteaceae

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Grevillea anethifolia – Proteaceae

This species is a handsome bushy shrub to 2 metres (over 6’) in height with creamy white flowers and finely divided foliage. Around Esperance it favours silt/sand loams over limestone and is usually encountered near roadside culverts and river/creek flood zones where soils are mostly well-drained, but may become inundated for short periods when waterways are in flood.

In WA Grevillea anethifolia has a scattered distribution from the NE of Esperance, then to Lake Grace, Southern Cross and Zanthus (on the Nullarbor), it is also found in SA and southwest NSW. In WA there is another very similar looking Grevillea (G. paniculata) that is further west and northwest from this species. The most obvious difference is G. anethifolia has hairy branches, covered with straight white, vertically appressed hairs, whereas the branches of G. paniculata have none. Also the style summit of G. anethifolia is truncated, but pointed in other species. Yet another similar looking species (G. biternata) occurs further north again, but is a considerable distance from the Esperance region.

The flowers although numerous are reasonably small and therefore probably pollinated by insects. Nevertheless, the shrub is quite ornamental being enhanced by the fine (slightly prickly) divided foliage. Flowering time varies depending on local rainfall, but is recorded from August to December, although when weather conditions are favourable, plants can flower at least twice during this period.

Grevillea plurijuga subsp. superba

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Grevillea plurijuga subsp. superba

Of the two Grevillea plurijuga subspecies, subsp. superba is generally taller and more upright to 2-3 metres (6'-10'). The flowers tend to be more numerous and slightly larger than subsp. plurijuga, often around 5 cm (2") in total length. They are situated differently too, being on a long more vertical flowering stem with the flowers standing ABOVE the foliage. The leaf segments are also thicker, which is another feature that distinguishes this subspecies.

Grevillea plurijuga, subsp. superba is common to the north of Esperance and the NE around Mt Ridley, where it can be found in shrubby mallee heath, on sandy loams especially when over limestone. The large red flowers attract honeyeating birds between October and December.