Effects can include a large range of features and tools. The OctaneRender plugin for Maya categorizes volume mediums, hair & fur, instancing, and particles as effects components. Figure 1 shows an example of rendering a volume using Octane for Maya. Figure 2 shows how Maya hair can be used to simulate grass which is then rendered using Octane.
Figure 1: A volume rendered in Octane for Maya
Figure 2: Hair render using Octane for Maya
It is important to note that while Maya hair and simple Paint Effects strokes can be rendered using Octane for Maya, volumes will require a plug-in in order to render VDB format volumes. This is because Maya does not support the VDB format. The OpenVDB project (http://www.openvdb.org/) offers scripts that can allow for importing VDB files which can then be rendered in Maya.