Greetings fellow Foxies,
To paraphrase Tom Gleeson, this year I am really into roots.
For years I noticed that Kickbush (Styphelia acervata, 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”
To paraphrase Tom Gleeson, this year I am really into roots.
For years I noticed that Kickbush (Styphelia acervata, 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”
 Old plant in autumn. Green part actively growing, yellow water stressed (dormant), brown dead |  Actively growing plant with tubular flowers |
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. A bit 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
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. A bit 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
 Rootstock splitting stem base cross section |  Normal (sheoak) type stem base cross section |
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 that greatly increases the plant’s access to water and nutrients.
- Tough and spiny leaves, which often 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.
Developing Kickbush berry To enable pollination and seed distribution over a distance, Kickbush has: -
Interesting little plants
- 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’
A section through the top of one shows why they are called ‘mound plants’
Dead vegetation and soil trapped in the plant forms a mound
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.
 |  Lepidosperma brunonium |
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 (or rush)
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
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 (or rush)
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
Sandbinding root mass in left side of the plant above
Sand binding root mass The cluster roots were amazingly dense and resisted concentrated blasting from the hose.
Cluster roots are encouraged to form where there are sources of 'bound' phosphorus as in leaf litter and accumulated dust as in the left handed side of the kickbush.
Cluster roots are encouraged to form where there are sources of 'bound' phosphorus as in leaf litter and accumulated dust as in the left handed side of the kickbush.
| Incidentally there is an upright growing kickbush relative in Foxes Lair that has taken the species name Styphelia pallida (right image). I suspect that this does not have rootstock splitting or any association with sand binding sedges but couldn’t find dead specimens to find out. |  |