This section is from the book "The Gardener's Monthly And Horticulturist V23", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The American Agriculturist says this belongs to the flamula group, and says its flowers - something remarkable among these plants - are yellow. The plant is rather slender and delicate, having less robust stems, than the other climbers. The foliage, of a fresh and pleasing green, is more finely cut than in the other species, each leaf consisting of three to five sharp-pointed leaflets which are themselves cut or lobed. The flowers are solitary, of only four spreading sepals, and are about 1½ in. across; their color is a pale lemon-yellow. This plant, coming from the higher mountains of Chinese Tartary, is a comparatively recent introduction. As may be inferred from its origin, it has proved perfectly hardy in the severe climate of New England, and this, together with its delicate habit, its very free growth, and the unusual color of its abundant flowers, will make it very popular when it becomes better known. It blooms in late summer, and its flowers are soon succeeded by globular clusters of fruits, the long feathery tails to which are of a very pale green, and about as showy as the flowers.
It is Clematis gravedens botanically.