Vray render fur grass

I am trying to render a square of grass with Fur Vray object, with default definitions.
Unfortunately I get an unexpected strange very thin dark threads, which don’t look as what I expect to get.
What can be the reason for that?
I use Sketchup 17 + Vray next.
Important to say that it is not all time like that, and i didn’t succeed to find out when it is happen, and when is not.

You just need to bump up your ‘Distribution’ which is also your grass blade density. Right now they are sparse by default. See example of different settings being adjusted.

Default Fur…thinly spaced and less realistic:

Denser Fur with less taper and shorter length to look more like fresh cut lawn:

Thinner, longer fur with variation in direction, length and gravity (or bend) applied to look more like un-mowed grass. Like my lawn at home right now:

In addition to @eric-s’s advice, you might also try a more uniform texture for your grass, perhaps one of V-ray’s default grass materials.