The easy way is to save one animated primrose as a vob and load that into the ecosystem.
To animate primrose: set end keyframe; then change properties such as droop, leaf size, etc and set first keyframe. Right click in object properties to save object and save as a vob. This won't create variation in the animation, to do that you would need to save out several different animations and add them all to the ecosystem.
Looks good I just tried it with ecosystem paint and 11,000+ primroses. No noticeable affect on system resources. David