I did purchase a set of these models to take a look at them.  The quality is very, very good.

The grass leaves are fully modelled and only the small flowering parts are made from alpha planes. Texturing of the leaves and the alpha planes is superb work. Because the leaves are fully modelled, it is unlikely that anyone would get those nasty black dots or other artifacts in their renderings. Instead, one should have very high quality renders, time after time, under a wide variety of conditions. 

It is clear these have been made in Xfrog: flowers, leaves and stems are separate sub-components. For  scene builders in many applications, this  is an advantage as the alpha flower portions and the flower stems could be deleted if the application does not support use of alpha planes.

As you would expect from such high quality models, the poly count is relatively large, although it plainly has been optimized to be as small as possible. Models in Pack Number 3 range from     10.12 MB (99, 862 faces) to .7 (7,500 faces) MB in file size and poly count.  Incidentally, the optimization is accomplished very well - faces and vertices are placed in the best possible places to maintain the curves of the grass leaves and stems, while using the fewest possible polys. All models have triangular poly shapes.

Click on the attached pic to get a closer look at the detail.

As a professional model-builder, I would comment that these models are very high quality for the price - indeed, this is a bargain (nay, a "steal!") for the commercial market, and I hope to see more of such plants. (even, considering the prices are in Euros......)