It's been about six weeks since I planted the "Betta bulbs" (Aponogeton sp., allegedly A. ulvaceus), so whatever's going to grow has probably grown. Apparently I planted four in the main tank, one in the Macropodus tank, and two in the plant tank.
They grew well in the plant tank. After about two weeks, one of the bulbs had sprouted, and after another week a flower spike broke the surface of the water. While the first one didn't expand, the plant has produced another four in rapid succession. The young inflorescence looks like the top picture. As it expands it ends up looking more like the lower image.
Shortly thereafter, the second bulb in the plant tank started growing, and it too has produced a succession of flowers. Both plants have also produced floating leaves.
Things were a bit different in the main tank. One of the bulbs floated up fairly soon, apparently dead. A second one eventually made it to the surface, and appears to be dead as well. I'm not entirely sure what happened to the other two - there's one plant that's either a young Aponogeton or a Cryptocoryne sucker, and another leaf that could be a second bulb. In both cases, the plants are small and could easily be something else. I haven't seen any sign of the bulb in the Macropodus tank, but that tank has become so heavily overgrown (since I upgraded from incandescent to compact fluorescent lighting) that I'm really not sure that I would be able to find it if it were growing.