​Greetings fellow Foxies,
 
To paraphrase Tom Gleeson, this year I am really into roots.
 For years I noticed that Kickbush (Astroloma acervatum, previously named Astroloma pallidum) often had dead or stressed patches, in its otherwise healthy neat little clump.
Recently I read about rootstock splitting in Astrolomas in the thrilling (for me)  book “Unravelling the Secret Lives of Plant Root Systems”
 
Aha, a new project for Detective Doug!

In most plants the main stem and taproot is a single cylinder containing the conducting vessels for water up to the branches (xylem), and sugars down from the branches to the roots (phloem). When the roots run out of water the whole plant is affected.
A rootstock splitting plant has a bundle of individual cylinders each with a bark coating that connect from a lateral (side) root to a side branch. Sort of like the insulated wires in an electric cable. If the soil on one side of the plant is particularly dry, only the branch fed by roots from that side are affected

Kickbush plants form mounded mats on relatively open areas in sands or gravels. They have amazing adaptations for poor and shallow soils. These include

• Rootstock splitting root system
• Both a deep tap root and shallow woody lateral roots
• A unique ericoid mycorrhiza consisting of long root hairs growing out of the woody roots, which become infected by fungi, which greatly increases the plant’s effective root area.
• Tough and spiny leaves that can become yellow and dormant in summer
• Prostrate stems that spread along the ground and send up vertical twigs to form a mat that traps soil and leaves. This reduces the surface soil temperature and help the plant retain moisture.

To enable pollination and seed distribution over a distance, Kickbush has: -

• Tubular flowers that are pollinated by native bees (that can fly further than European honeybees) using buzz pollination.
• Seed are drupes (berries) that are eaten by birds and animals and spread in their dung. They are bush tucker and the Kickbush name comes from early settlers kicking the prostrate bushes over to look for ripe berries underneath (Noongars use a stick to pick through the leaves).

 
             Interesting little plants

I found three dead plants: one had been killed by a borer and the others apparently from old age.
​A section through the top of one shows why they are called ‘mound plants’

​Another dead plant that I excavated had two sedges alongside it. The large sedge (Lepidosperma brunonium) in the image below had a very vigourous root system that separated from the Kickbush on excavation.
 
I took the excavated plant home and washed it out to remove soil and trapped debris.
The bottom image below showing a side view of the washed Kickbush shows the relatively small taproot with large lateral roots radiating out just below the surface. The laterals would have sent out smaller roots to explore for gaps in the dense or gravelly subsoils and produce the long root hairs that were colonised by fungi in the growing season.

​I took the excavated plant home and washed it out to remove soil and trapped debris.
The image below showing a side view of the washed Kickbush shows the relatively small taproot with large lateral roots radiating out just below the surface. The laterals would have sent out smaller roots to explore for gaps in the dense or gravelly subsoils and produce the long root hairs that were colonised by fungi in the growing season.
Above the soil surface main stems radiating out in a circle produced upward facing foliage that trapped debris. Washing the plant was no mean feat as one side of the kickbush had been colonised by densely packed cluster roots from the small sedge
The thin ‘root’ projecting below the root on the left is a sedge rhizome (underground stem) that ran below the soil surface to shoots and the root mass in the Kickbush

Sand binding roots are common in monocotyledons (grasses rushes and sedges) in sandy soils in the Australian bush, but I have never noticed them before.
 They were amazingly dense and resisted concentrated blasting from the hose. 

​Greetings fellow Foxies,

The bush in Foxes lair is still benefitting from a burn in December 2009, particularly on gravel soils. In the image below taken from the Breakaway Walk area last year, pink Mirbelia dilatata flowers show the burnt area compared to sedge dominated bush to the left that hasn’t burnt for 40 years.

​There is also a great resurgence in lovely hairy flowered Jacksonia epiphyllum on the entry road in late October. Last year I happened to get a pic of a rare weevil and returned regularly to see if I could collect a specimen for the WA Museum. Alas no more rare weevils but many other interesting little beasties.

For a visual exploration of other wonderful beasties click this Google Photos link

The balga Xanthorrhoea preissii, a grass tree, is a striking part of our bush that was use by Noongars for medicine, tools and sustenance. Grass trees are monocotyledons but neither grasses nor trees.
 Carbon dating has found grass tree ages of up to 1,000 years. Also, they have special contractile roots that pull seedlings underground so that plants on sandy soils may not develop an above ground stem for 10 to 30 years. I reckon that the five-metre plant I found in Candy Block must be ancient. Unfortunately, twenty-eight parrots are now attacking its new growth.
 
The grass tree at Foxes Lair is the smaller Xanthorrhoea brevistyla that lacks an above ground trunk. It is an insect magnet when flowering in November.
 
I regularly see severe insect attack on balga flowering spikes and brought one home for examination. The green stem had frequent reddish- brown sunken lesions with gum exuding from small holes. The split stem revealed tunnels containing bardi grubs, surrounded by reddish brown fungal infection. Once again, a canker fungus that affects eucalypts and other shrubs

Interestingly, a previous investigation on wandoo crown decline in Foxes Lair  found a similar combination of insects and fungus. The fungus causes severe damage to trees and shrubs. Fungus doesn’t seem to affect the balga trunk, presumably because flowering spikes naturally die before it can spread further.
​
​The bardi grubs are larvae of longicorn and cockchafer beetles. They have tunnelled up through the entire flowering stem.
The flowers and seeds were attacked by a brownish caterpillar that eats them under a protective cover it makes from its frass (poo) and silk.

​Last year I received a shock when one of two apparently healthy balgas that I had photographed earlier snapped off at mid stem

​The centre of a normal trunk is filled with living fibrous material above a woody cone-shaped base that remains long after a plant has died. The living centre is surrounded by old leaf bases held together by natural resin, which provides support and excellent fire protection.
The fibrous centre of the dead balga was completely replaced by a soil-like material containing wireworms, which were attacking the interior of the surrounding leaf bases

​As Noongars ate bardi grubs that were in the centre of dead balgas, I suspect that they had chewed out the living material before wireworms moved in.
This balga had been surviving with a decayed centre for some time until the weakened stem snapped. It is a natural process and dead remnants can be attractive in their own right.
 
Unfortunately, increased in Australian ringneck parrot (twenty eight) numbers are causing premature balga death from them continuously chewing the new growth.

​ Greetings fellow Foxies,
 
There have been many comments recently about widespread shrub death in Foxes Lair due to the exceptionally dry spring and summer.
Certainly, there is more death than usual, but this doesn't explain the scattered pattern in Foxes Lair with dead plants next to healthy ones.
Luckily my esteemed colleague Detective Doug volunteered to investigate this problem.
 
The great man randomly selected two each of dead and healthy Dilwynnia laxiflora (pea flower) plants for examination

​Dead plants.
The roots were very bent and thickened, particularly the tap root that snaps easily. Borer channels were on both the outside and inside, including one that contained a jewel beetle emerging from its pupal case.

 Problem solved?
No, being a true scientist, Detective Doug insisted on also examining the healthy specimens
Roots of both live plants had also  been attacked, although to a lesser extent than dead plants.
The first plant had a few minor lesions but otherwise appeared normal. However when split in half lengthwise the root was hollowed out and contained a hibernating? jewell beetle. These beetles are common on pea flowers in October so presumably they hibernate until spring.

The second healthy plant showed evidence of insect attack that appeared to be confined to the surface. However, when cut in half it was obvious that insects had entered and tunnelled up the centre of the root. While doing this they brought in spores of a canker fungus, shown by the blackened areas. This fungus invades healthy tissue, blocks water and nutrient transport and kills the plant. 
​
Conclusion
These plants are routinely attacked by borers and may survive for more than a year until invading canker fungus kills them or they snap off. Increased water stress from extended dry weather hastens plant death.
Case closed
​
Interestingly, a previous investigation on wandoo crown decline in Foxes Lair  found a similar combination of factors.