This is definitely a dog's tooth, but it's biting itself. Rhizomes are very aggressive, and they have the ability to exert strong physical force to get where they want, even to puncture a neighbor. Competition among species can be violent, even in plants. Another important implication of this puncture is that it destroys the vascular system of the rhizome, preventing herbicides from translocating and killing buds. This is an important form of herbicide resistance.
Weed biology can be very weird sometimes.
It and its cohorts litter the surface of this Ontario field. Although the rhizome is dried out, it still has the ability to germinate and grow. Tolerance to drying is an important weedy adaptation in buds of perennial weeds. Next to this shoot are some other emerged and established shoots. Quackgrass shoot emergence from the bud bank is staggered over time, and this makes precise timing of herbicide applications difficult if they must be sprayed at a particular stage of development.