Heirlooms, they will produce genetically true plants and become specialized to our particular place in the world over time. I also saved mustard seed this season for Fall and have Saison de Quatre heirloom lettuce setting seed in the garden.
Seeds marketed as heirloom cost more on the premise that one will save seeds. But there are many hiding in plain site that are heirloom, like mustard, okra ,many of the lettuces and the Contender beans. The sure way to know is search the name of the plant, check the year of it's pedigree and ta-da! you will know. Example: a seed bred in the early 1900's or before is heirloom.
|It is nice if they dry on the plant but it is not required.|