Our native Clematis vitalba is like Clematis tibetana a climbing shrub. Its scented greenish-white flowers are visible throughout most of the summer. The whitish, fluffy seed heads are found in the fall and winter.
On each seed head there are about 20 individual seeds, each with an awn, the silvery trail some 40 mm long. The trail is designed to help carry the seed upon the wind, drifting it away from the parent plant.
Seeds require winter-chilling to maximize germination. Hydrated seeds do not survive long, and the dense feathery seed loads hanging in plants over winter can be regarded as a dry, aerial seed bank from which seeds can fall sporadically over the winter.