Contractile roots are not present on any stoloniferous
Lilium species. These species adjust their height in the soil not by pulling themselves down (what contractile roots do), but by growing a new bulb at the level of their choosing, be that deeper, shallower or at the same level as the original bulb.
This year was extremely rainy for us throughout the spring and summer. Although this seedling bulb had been untouched for 3-4 years in the ground, and certainly by then would have found its happy place (correct height) in the soil, it re-adjusted this year. The new bulbs (small arrows) grew 3/4 inch higher this season. Last year's bulb (large arrow) had produced five blooms, a respectable amount for
Lilium michiganense, but it is clear that the much larger bulbs formed this season benefited by the extra moisture.
Notice that roots only last one year (approximately late summer to late summer). As with all stoloniferous lily species, all roots from the old bulb will die by fall's end.
Lilium michiganense