There are some plant species (eg some Mimulus I believe), which are so efficient at vegetative increase that there may be only one clone for miles and they rarely bother to set seed. Also in horticulture a sterile clone or hybred of a plant species may have advantages such as not self seeding and thereby being invasive or producing poorer forms as seedlings, such as in the case of Iphion cultivars as mentioned by Alberto. Double flowered forms of species plants may well be freek seedlings where the sexual parts of the flower have turned petaloid, rendering them sterile. They can still be pure species material. Other plants self pollinate such as some Amarylliads? Ficus and species of Sorbus- effectively producing clonal offspring and being an evolutionary "dead ends" unless they 'sport' or manage to cross pollinate with something else. Peter (UK) On Mon, Jan 30, 2012 at 5:29 AM, The Silent Seed <santoury@aol.com> wrote: > > This is the first time I've ever heard of an actual species (of anything) > being sterile beyond artificial damage, such as neutering, or radioactive > exposure, etc? Is it possible that the flowers simply are not being > pollinated ? When I do not pollinate the flowers, they do not set seed. Is > this what you mean? >