Trad is the weed Tradescantia fluminensis (also known as T. albiflora). While the privets are the most important woody weeds, trad can be a big problem on the forest floor. It covers the ground in a thick mat and prevents the regeneration of rainforest seedlings. It also smothers four Australian native species that are closely-related: Aneilema acuminatum, Aneilema biflorum, Commelina cyanea and Pollia crispata.
Trad doesn't produce seed, at least in Australia. As a result, if you remove the vegetative bits, it doesn't come back unless it's re-introduced, say by floating in on a flood. That said, killing all vegetative bits is difficult, although far from impossible. It's a weed that's worth a bit of study, because it's easier to control if you know just what conditions favour it, and what its weak points are.
Where trad isn't growing as a thick mat, it can be weeded by hand. Wear gloves (surgical gloves are best for delicate weeding), because trad sap can cause an allergic response. Important points:
Controlling trad effectively is very rewarding, especially when you see native ground covers and tree seedlings stimulated to germinate once the mat of weed is removed.
Trad grows in damp, shady places as a thick mat. Unless you are fond of lost causes, or have vast resources of labour, don't try to hand-weed large areas of such thick monocultures. One effective strategy is to attack the mat in the following stages
The long term method
Trad thrives in partially-shaded, moist and fertile areas - just the kind of places that would, in its absence, regenerate rainforest. But even trad has its limits. It struggles to grow in mature rainforest, especially where a diversity of vines has helped to close the canopy. The mature trees are also highly efficient at taking up nutrients as soon as they are liberated from the fallen leaves. With good management, regenerating rainforest will attain that resilient stage more quickly, shading and starving out this extraordinary weed.
This is a trad 'corral', where hand-weeded or raked trad can be dumped. Then, you MUST return to spray with glyphosate herbicide every few months to ensure that it rots down. On a floodable site like this one the corral needs to be supported by some substantial stakes. Otherwise it would be swept away when the flood plain becomes a lake. In between floods, it's sufficient to rake trad into piles for spraying, although brush turkeys and lyrebirds can be a problem. They will rake through the rotting trad for insects, scattering it in the process. Even worse, turkeys may incorporate it in their nest mound, where fragments are likely to regrow. Corrals aren't very pretty, but they can help to overcome these problems.
Before you kill it, have a close look at a trad flower. Around the stamens you will see some fine hairs. Under the microscope (photo below), these are seen to be strings of cells, so transparent that you can see mitochondria streaming along strands of protoplasm.
Photo Michael Reid
You can see protoplasmic streaming (cyclosis) in this video - worth a visit to see how lively those floral hairs of tradescantia are. The tiny black specks streaming along the strands of protoplasm are the mitochondria.
Our trad is sterile
Don't worry if you see trad flowering, because it won't set seed. This is because it was introduced into Australia as a self-sterile clone. There is always the danger that another clone could arrive to pollinate and set seed with our resident one.
If that happened to us, that would make trad an even more serious weed.
More information can be found from the following link:
The potential for biocontrol of trad is being investigated in New Zealand. Three beetle species from SE Brazil, where trad is a native plant, appear to show promise. One of these eats the foliage (Neolema ogloblini), another the growing tips (Neolema abbreviata), while yet another eats the stems (Lema basicostata).