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Parramatta and Hills District Group

Group News

Dr Peter Weston on 'Gondwanan Plants of the Sydney Region'  25/11/17

Testing the Gondwanan hypothesis: Findings

The evidence suggests that the Gondwanan hypothesis does hold to some extent but that the story is not so simple. The evidence also suggests that dispersal across oceans has played its part in the distribution of our southern plant genera.

To quote:

“The findings suggest that disjunct distributions in Proteaceae result from both Gondwanan vicariance and transoceanic dispersal. Our results imply that ancestors of some taxa dispersed across oceans rather than rafting with Gondwanan fragments as previously thought. This finding agrees with other studies of Gondwanan plants in dating the divergence of Australian, New Zealand and New Caledonian taxa in the Eocene, consistent with the existence of a shared, ancestral Eocene flora but contrary to a vicariance scenario based on accepted geological knowledge.” (Barker et al, 2007)

So, were Hooker and Darwin both right and wrong?

To sum up: scientific study has supported the Gondwana theory as the origin of some species, while other species arose from individual mutations which were then spread by wind and water. For some species, both processes have played a part.


Westhead Challenger Track 7/10/17

Marilyn Cross & Lesley Waite

On 7th October, 2017, APS ParraHills went to Westhead Ku-Ring-Gai Chase NP for a bushwalk along the Challenger Track which runs from the roadway along the ridgetop until it meets the cliff top, looking out over the mouth of the Hawkesbury River towards Brisbane Water National Park. 

The terrain is sandy over Hawkesbury sandstone but with underlying hanging swamp in places. The vegetation is heath-like with low growing trees until the last section of the track which becomes a denser woodland until the cliff top is reached.

Table 1


Species: Westhead

Botanical Name

Terrain

Robinson (2003) Page #

1

Actinotus minor

ridgetop

124

2

Angophora hispida

ridgetop

24

3

Bauera rubiodes

ridgetop

156

4

Boronia ledifolia

ridgetop

115

5

Boronia pinnata

ridgetop

116

6

Boronia serrulata

ridgetop

117

7

Burchardia umbellata

ridgetop

231

8

Calytrix tetragona

ridgetop

28

9

Conospermum ericifolium

ridgetop

93

10

Conospermum longifolium

ridgetop

93

11

Dampiera stricta

ridgetop

173

12

Darwinia fascicularis

ridgetop

29

13

Dianella caerulea var. producta

ridgetop

232

14

Dillwynia floribunda

ridgetop

77

15

Epacris microphylla

ridgetop

107


Table 2

Species: Westhead

Botanical Name

Terrain

Robinson (2003) Page #

16

Eriostemon australasius

ridgetop

118

17

Eucalyptus umbra

ridgetop

44

18

Gahnia spp.

ridgetop

289 - 290

19

Gompholobium grandiflorum

off the ridgetop

80

20

Grevillea buxifolia

ridgetop

94

21

Grevillea sericea

off the ridgetop

96

22

Grevillea speciosa

ridgetop

97

23

Hibbertia bracteata

wooded area

159

24

Hibbertia spp.

ridgetop

158 - 162

25

Hybanthus vernonii

ridgetop

224

26

Isopogon anethifolius

ridgetop

99

27

Kunzea capitata

ridgetop

51

28

Lambertia formosa

ridgetop

99

29

Lasiopetalum ferrugineum

off the ridgetop

216, 217

30

Leptospermum parvifolium

wooded area

54


Table 3

Species: Westhead

Botanical Name

Terrain

Robinson (2003) Page #

31

Leucopogon microphyllus

ridgetop

109

32

Micromyrtus ciliata

ridgetop

60

33

Mitrasacme polymorpha

ridgetop

188

34

Patersonia glabrata

ridgetop

228

35

Persoonia levis

wooded area

101

36

Philotheca salsolifolia

ridgetop

121

37

Pimelea linifolia

ridgetop

220

38

Pultenaea daphnoides

wooded area

85

39

Pultenaea ferruginea

wooded area

85

40

Sphaerolobium minus

ridgetop

89

41

Tetratheca ericifolia

ridgetop

221

42

Woollsia pungens

ridgetop

113

43

Xanthorrhoea arborea

clifftop

278

44

Zieria laevigata ssp laevigata

ridgetop

122




Mount Annan Plantbank Visit 27/7/17

About a dozen members and friends visited the Mt Annan Plantbank on Thurs 27 July. It was a beautiful day – cool and crisp with hardly a cloud in the sky. We were met by our guide at the Plantbank entrance and proceeded on our tour of the working areas of the facility.

The general aim of the Plantbank is to preserve and study the seeds of all 6000 plus plants in NSW and the 25000 plus plant species in Australia. Staff mount gathering trips periodically to bring in seed from different species. Samples are usually representative of the plants in the wild rather than just the best specimens.  Most are dry land plants where the seed can be preserved fairly easily. The active part of the seed is separated from the surrounding chaff, it is then dried at 15DC and 15% humidity, then sealed in metal foil packets and stored in the vault at -5DC. For most species this will maintain the ability to germinate for many decades up to hundreds of years. Not all of the sample is stored at Mt Annan – parts are forwarded to other plantbanks around the world. Mt Annan’s major partner in this process is the Millenium Seedbank at Kew Gardens in the UK.

Wet area plants and rainforest plants are not as easy to handle. The seeds are often larger with more flesh and require specialised techniques to preserve them. Plant tissues and seeds are prepared in special bottles and then stored in the vapour from liquid nitrogen at -196DC. This process preserves them almost indefinitely.

The Plantbank building is an excellent facility and cost $20 million to build. It has been going for some years now and will take another 20-30 years to accumulate all the species of interest – it has plenty of capacity to accommodate this. As existing samples age there will also be the need to replace them periodically. The Plantbank also has a nursery to check seed viability in a practical way and this also provides specimens for the Botanic Garden and various ecological experiments.

Our group really enjoyed our visit – it was stimulating and inspiring to see the work under way.



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