© Pete Saloutos/Panoramic Images (Maine Title Image Large)
Featherfoil (Hottonia inflata)
Featherfoil is a short-lived aquatic herb with an entirely submerged, spongy, densely leafy, hollow stem. The successive segments of the stem become progressively shorter bearing a terminal umbel of racemes. The white flowers are small (5-8 cm) in whorled verticils of 2-10 at the joints. The leaves are sessile, or nearly so, oblong (2-6 cm) and divided into narrowly, linear entire segments.
Known populations occur in vernal pools in southern Maine. The species is believed to be a winter annual, with seeds germinating in the fall and resuming growth in the spring.
You can learn more about this species by visiting its page on the Maine Natural Areas Program's website.