Gap in convergent evolution?

[bri-k]

Just yesterday I planted a patch of turf with Bouteloua gracilis, which is native to North America, and so are many other species that can be grown as turf (e.g. Festuca rubra, Agrostis pallens, etc.). After thinking about this further, though, I realized that most of the cultivated grasses native to North America are bunch/tussock grasses, which leads me to agree with @pfau_tarleton that “maybe steppe environments aren’t the center of turf-forming grass evolution.” On steppes, and especially in tall-grass prairie, the grasses are… tall, unsurprisingly. Because they need to compete with so many other plants for light, they’ve evolved to grow much taller than is desirable in a turf grass. In contrast, I’ve seen many grasses growing on sand dunes that would be perfectly suitable for turf because they tend to be low-growing and mat-forming, presumably due to the lack of competition for light and the necessity to essentially float above the sand by creating a raft. Perhaps it’s environments like sand dunes, not steppeland prairie, where most of the spreading, sod-forming grasses like Cynodon dactylon and Cenchrus clandestinus originated.