Just as an update for anyone who might be interested--I went back to the store and bought some more. Overall, most of the kumquats were quite a bit larger and more spherical--the first bunch I bought were a bit smaller and more oval-shaped. Most of them still had the shrivelled-looking seeds, but I did find a couple of normal, average citrus seeds in there. I'm thinking that their prime harvesting season is just beginning. And it seems common for most seeds to be underdeveloped.

The issue is are they hybrids or heirlooms/open pollinated varieties. If they are hybrids then the seeds you save won't breed true. Hybrid seeds in the packet are the result of manual cross-pollination of at least 2 parent varieties. The seeds saved from those hybrid plants once grown, will revert to the parent stock or some strange combination of them. If your seeds planted and grown are heirlooms or open-pollinated plants, not hybrids, then yes you can save the seeds and re-grow them. Depending on what the plant is - self-fertile like tomatoes or insect pollinated like most flowers, they may or may not grow true. In some cases, like hollyhocks you will still get lots cross-pollination by insects so your saved seeds may change color etc. It all depends on how much you care whether or not the seeds you saved breed true or not. Many don't care, many do. Some research on cross-pollination will explain this in more detail. ;) Dave

Depends on the parents that made the hybrid. Many commercial hybrids grown for that use are actually pretty phenotypically (how they look) similar. The differences usually are in other characteristics such as disease resistance or yield.

I just ran across this site because I was looking for a cause of this and if and how to plant my tomatoes. I have 2 tomatoes, on the same vine that were bought in the store about a week ago. My house temp is about 68-70 degrees and I have sprouts that broke the surface of the tomato. It looks rather cool but like I said, I don't know if and how to plant them or if I can this time of year. I just put a link on here, not knowing what I am doing to see if you can get the picture. But, can I just plant it inside, whole in the tomatoes so that I don't mess up the cause of the growth?