Much of the heritage of our plants has been eradicated. However, there is now a view that heritage seeds need to be used, as well as protected. Since the industrialisation of farming methods our heritage of plants seem to have largely disappeared. There are concerns which deal only in heritage seeds/plants, readily found on the internet.
Heritage seeds come from open-pollinated plants that pass on similar characteristics and traits from the parent plant to the child plant. There is no concrete definition that every gardener uses to define heritage plants.
Some people state that heritage plants are those that were introduced before 1951, while others state that heritage varieties are those introduced before the 1920s. In general, you should consider heritage to be seeds that are possible to re-grow and pass on from one generation to the next.
One important thing to note for heritage plants is whether they are organic or non-organic. In most cases, heritage plants are organic because they are generally only used by small-scale gardeners who do not use pesticide or other harmful chemicals.
However, there may be minor cases when chemicals do get involved since heritage plants do not always have a similar level of innate protection that hybrid and GMO plants provide against diseases and pests.
Remember, heritage refers to the heritage of a plant, while organic refers to a growing practice. Heritage plants are generally known to produce better taste and flavour; their fruits/vegetables are also known to be more nutritious. Being less expensive to maintain over the longer period and taking more care than their counterparts is worth the effort you put in.
Most importantly you would also be playing a part in preserving the genetic diversity of plants, thus ensuring people in the future would be able to enjoy. The fun of gardening is the challenge to do better. Preserving such a heritage will ensure the future will be better.