My last two homemade soups have yielded strange results with the celery. Though last week's split pea and this week's mushroom barley simmered for 3 and 4 hours respectively, in both instances the celery did not soften enough. In both cases I left the celery in a fairly large dice, between half an inch and an inch in diameter depending on what part of the stalk they were cut from. But in the past, this never mattered when simmering for so long, the celery always came out meltingly soft. It seems to be the outer part of the celery that suffered from this, because once you bite into a piece and feel its unusually tough exterior, the inside gives way and dissolves in your mouth as normal long-simmered celery would. I also included carrots in both these recent efforts, left even in larger pieces than the celery, and the carrots were perfectly soft, as was everything else that went into both soups. The only thing I can think of is that both stalks were purchased at the same grocery and both were the same brand, but the name escapes me. Did I just get unlucky with a bad brand, or what other fluke may have caused this?