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Australian Plants Society NORTH SHORE GROUP

Ku-ring-gai Wildflower Garden

SYDNEY SANDSTONE FLORA

Formation of Sydney Sandstone 300 million years ago the rocks of Antarctica were uplifted to form a massive mountain

range. At this time Australia and Antarctica, as part of Gondwana, were adjacent and

situated near the South Pole.

200 to 250 million years ago erosion of these mountains produced vast quantities of

sand that was carried by a huge river system across southern Australia from Antarctica

until it reached the present east coast. It deposited the sand into the

Sydney Basin and over millions of years these sands were

consolidated into sandstone up to 50 metres thick.

Geology of the Sydney area There are 3 major groups with minor layers.

1. Wianamatta Shale

2. Hawkesbury Sandstone (HS)

3. Narrabeen Sandstone

The Wianamatta Group is essentially shale, acidic and moderately

fertile. In Ku-ring-gai it is on the higher areas. Typical vegetation is

found on the higher slopes of Sheldon Forest and Dalrymple Nature

Reserve.

Beneath the shale lies Hawkesbury Sandstone which supports a sandy

acidic soil, pH 5.5 to 4.

Did you know that?

Sydney sandstone was formed over 200 million years ago.

In spite of being low in nutrients, it has great diversity.

Its area extends roughly from the Hunter River to the Shoalhaven River and to

the western edge of the Blue Mountains.

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Narrabeen Sandstone located under the Hawkesbury, is from an earlier time and has a

somewhat larger component of shale.

Area The Sydney area is located roughly from Newcastle to the Shoalhaven and west to the

western edge of the Blue Mountains, an area of 23000 square kilometres. It contains the

catchment of the Nepean-Hawkesbury Rivers (excluding the upper Wollondilly River).

In the centre of the Sydney area is the Cumberland plain with its shale soil. To the north

is the Hornsby Plateau, generally 200-300m above sea level. Here the major outcropping

rock is Hawkesbury Sandstone.

Soils Sandstone generally weathers to form grey/yellow sandy soils which are acidic with low

fertility. These support a very high diversity of plant species.

Although the KWG vegetation is essentially Hawkesbury Sandstone flora, it could be

influenced by the presence of Shale in some of the higher areas. Features include-

Tessellated pavements - Caused by weathering and erosion

Laterites- from iron and aluminium oxides, are remnants of a previous extensive

shale plateau surface. Identified by large irregular, rounded orange-red ironstone

nuggets. They provide some nutrients to the yellow soils and are able to support

low open forests. They are found on higher sandstone soils and in Ku-ring-gai

there are examples in the vicinity of KWG and St Ives Showground.

Tessellated pavement Laterites

Vegetation types

A variety of vegetation types are found in Sydney Sandstone including heath, scrub,

woodlands and open forest which is the predominant type where trees are up to 30 m

high with a canopy cover of 30-70 %. It is in this vegetation type where many of the

beautiful sandstone wildflowers are found. In the deeper valleys tall open forest and

rainforest are present.

Sandstone communities

Endangered Ecological Communities There are several Endangered Ecological Communities including Sydney Turpentine

Ironbark Forest (STIF) and Duffys Forest Ecological Community (DFEC) which have

components of Sandstone.

Areas of DFEC are found in KWG.

Components include the dominant canopy trees

• Eucalyptus sieberi (Black Ash or Silver top Ash)

• Corymbia gummifera (Red Bloodwood)

• Angophora costata (Sydney Red Gum)

• E. capitellata or E. oblonga (Stringybarks).

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Eucalyptus sieberi

Two major communities, Sydney Sandstone Ridgetop Woodland (SSRW) and

Sydney Sandstone Gully Forest (SSGF) are found in Sydney Sandstone.

SSRW is found on the more exposed ridges and plateaux with shallower soils interrupted

by outcrops of rock. Features found include tessellated pavements and laterites.

Characteristic tree species of SSRW in KWG are Corymbia gummifera, Eucalyptus

oblonga, E. haemastoma and E. racemosa. Patches of Banksia ericifolia and Hakea

teretifolia occur in open-scrub sites with poorly drained soil.

SSGF is generally confined to gullies and sheltered hillsides, particularly on the Southern

and Eastern aspects. It may have 3 units;

Open-forest/woodland where the main trees are E. piperita and Angophora

costata. Corymbia gummifera and Allocasuarina littoralis are also present.

Tall open-forest where the trees are E. pilularis and Syncarpia glomulifera. (This

assembly is not at KWG).

Closed forest with Ceratopetalum apetalum

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Ceratopetalum apetalum Tristaniopsis laurina Sandstone Gully Forest with closed canopy

Special plants • Melaleuca deanei Rare 3RC-

• Angophora crassifolia Restricted to the Ku-ring-gai plateau • Genoplesium baueri Rare 3RC- • Eucalyptus luehmanniana Rare 2RCa • Darwinia procera Rare 2RCa • Leucopogon amplexicaulis Restricted to the coastal districts of Sydney • Tetratheca glandulosa Vulnerable 2VC-

• Haloragodendron lucasii Endangered 2ECi •

(Key 2: Geographic range < 100km 3: Geographic range > 100km E: Endangered species in serious risk of disappearing within 1 or 2 decades . R: Rare in Australia but not currently considered endangered or vulnerable. V: Vulnerable not presently endangered – risk of disappearing over a longer period C: Population reserved – Ca : Adequately - C-: Adequacy unknown -Ci-: Inadequately reserved )

Melaleuca deanei Angophora crassifolia Genoplesium baueri Eucalyptus luehmanniana

Darwinia procera Leucopogon amplexicaulis Tetratheca glandulosa Haloragodendron lucasii

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Sandstone Families and a selection of their plants A major division of the Flowering Plants is into Dicotyledons and Monocotyledons.

Dicotyledons – Family Fabaceae (Sub family Mimosoideae)

Other Wattle Species

Acacia echinula Acacia ulicifolia

Acacia oxycedrus Acacia linifolia

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Family: Proteaceae This family includes Grevilleas and Banksias and the state floral emblem, the Waratah,

Telopea speciosissima. Other species are pictured below.

Families: Myrtaceae and Rutaceae The family Myrtaceae includes the eucalypts and callistemons. The Rutaceae family has

slightly fewer species. Boronias may be the highlight of this family.

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Myrtaceae

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Family: Ericaceae One of the special plants of this family is Epacris longiflora (Fuchsia Heath), but there

are several other species with other attractions, e.g. Woollsia pungens which flowers for

many months and has a strong perfume.

The Lesser Families

There are many outside those common families above. These are sometimes designated

Lesser Families. Species include Christmas Bush, the mistletoes, the mint bushes, flannel

flowers and daisies etc.

Blandfordia nobilis Actinotus helianthi Brachyscome sp Prostanthera scutellarioides

The Monocotyledons The monocotyledons are the other large division of the flowering plants and include

(Poaceae) grasses, grass trees, lomandras, reeds, rushes and sedges. A large family that

people find fascinating is the orchid family, Orchidaceae. Microtis rara, Prasophyllum

elatum and Thelymitra ixioides have been selected as representatives of the family.

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Orchidaceae

Poaceae Xanthorrhoeaceae & Lomandraceae

(Grass trees and Lomandras)

Xanthorrhoea media Lomandra brevis

Sedges and Rushes

These are Families Cyperaceae, Restionaceae and Juncaceae.

Isolepis nodosa Baloskion tetraphyllum Juncus usitatus (Cyperaceae) (Restionaceae) (Juncaceae)

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Plants other than the flowering plants:-

Ferns and Fern Allies There are many ferns in the area and fern allies, one of which is Psilotum nudum.

Blechnum nudum Psilotum nudum

ACKNOWLEDGEMENTS These notes are based on the presentation given at the Australian Plant Society’s Get-

together in August 2012. They rely on the excellent photos taken by Wendy Grimm,

Mark Abell and Pat Pike.

REFERENCES

Alan Fairley and Phillip Moore. Native Plants of the Sydney Region 2010.

Les Robinson. Field Guide to the Native Plants of Sydney. 2003

For more technical books:

Belinda Pellow, Murray Henwood and Roger Carolin. Flora of the Sydney Region. 2009

Gwen Harden. Flora of New South Wales Volumes 1-4 2000

For identification, plant descriptions and a glossary refer to PlantNET, courtesy of The

Royal Botanic Gardens & Domain Trust, Sydney, 2011.

PlantNET, http://plantnet.rbgsyd.nsw.gov.au/

Produced for the Walks and Talks Program of the North Shore Group, Australian Plants Society. BJ 2013