From Wikipedia so not 100% reliable but -MKG wrote:That's a good point - what happens if you let cress carry on growing? I could Google it, but I'm feeling apathetic today.
Hmmm...Garden cress is a perennial plant, and an important green vegetable consumed by human beings, most typically as a garnish or as a leaf vegetable. The garden cress produces an orange flower suitable for decorative use and also produces fruits which, when immature, are very much like caper berries.
...Unmolested garden cress can grow to a height of two feet with minimal maintenance in a garden; however, the edible shoots are typically harvested just a week after germination.
