This 2015 Australian plant summary study made several points:
“Non-transmission of epigenetic marks through meiosis may be regarded as an epigenetic modification in itself..we should understand the implications for plant evolution in the context of both selection for and selection against transgenerational epigenetic memory.
Both epigenetic inheritance and resetting are mechanistically directed and targeted. Stress-induced epigenetic modifications may buffer against DNA sequence-based evolution to maintain plasticity, or may form part of plasticity’s adaptive potential.
In some cases the signature of the stress experience remains in the epigenome after relief from the stress, providing a “memory.” If this memory conditions the response to stress during subsequent development, the organism is said to be epigenetically primed. If the memory of the stress experienced by a parent conditions the response of its progeny, this epigenetic priming may be transgenerational.
Epigenetic and genetic variation co-evolve..epigenetic plasticity does not completely buffer evolvability and reduce the correlation between fitness and genotype, slowing selection.”
One of the summarized studies found that a transgenerational epigenetic change eventually silenced itself after the 40th copy!
The Are stress-induced epigenetic changes to DNA inherited across generations? study was cited, although it argued for the opposing viewpoint.
http://journal.frontiersin.org/article/10.3389/fpls.2015.00699/full “Transgenerational inheritance or resetting of stress-induced epigenetic modifications: two sides of the same coin”