01 March 2008 - 13:28, Tinman said
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Our ten volunteers and two staff took on the ehrharta population on the Ledge today. Here they’re ambitiously attending to the cracks and crevices in the CPS stone wall along the Ledge’s plateau:

Ehrharta erecta is one of the most invasive grasses around. It originates in South Africa and was brought to the US as a potential turf grass. Unfortunately, it was released from a lab in Berkeley about 20 years ago, and since then it has run rampant throughout the Bay Area. It is a perennial grass that produces seed year ‘round—unlike native perennial bunch grasses that seed only once during the year. It also loves to grow close up to other plants, and frequently can be found right inside a clump of native bunch grass.

Here is a closeup of what we’re up against. In this case, the ehrharta grass is growing throughout a very nice patch of yarrow (Achillea millefolium). Left alone, the ehrhart will shortly smother the yarrow in a dense, high turf:

It requires meticulous work to remove the ehrharta while leaving the yarrow, but it can be done:

This isn’t a one-time step, though, as the ehrharta seed bank in all the soils of the Bay Area is such that new shoots will be back up in a couple of months. Still, triumphs such as what we accomplished today keep us coming back!

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