A semi-shrubby, deciduous plant, growing 2 to 3 ft high; stems ribbed, more or less downy, brownish red. Leaves composed of three leaflets, the terminal one much the largest, roundish ovate; shallowly, unequally, and sparsely bristly toothed; the base slightly heart-shaped, or almost cut off straight; from 2 to 5 in. long and wide; the side leaflets are similar in texture, etc., but are only half the size, and are scarcely stalked. Flowers 3⁄4 to 1 in. long, produced from the joints of the stems of the year in dense short clusters, each flower on a downy stalk 1 in. or less in length. They are tubular at the lower half and swollen at the base, the four sepals curling outwards and backwards towards the end, deep blue outside, downy. The flowers are unisexual, but both sexes appear on one plant. Seed-vessels with feathered tails.
Native of Central and N. China; introduced in 1837; flowering from July to September. It is one of a group known as Tubulosae, whose four sepals close up and form a half-tubular flower of the same shape as hyacinths; to this group C. stans as well as other minor species belong. They are notable for the large leaves and robust, although semi-herbaceous growths.
var. d avidian a (Verlot) Hemsl. C. davidiana Verlot. – This variety is somewhat taller than the type but similar in foliage and habit. The flowers are indigo-blue, the base tubular, but the four sepals spreading (not curled back as in the type) and also larger and longer. It is also distinct in being dioecious, male and female flowers being borne on separate plants. It is perhaps the most desirable of the section Tubulosae.
This variety was described (as C. davidiana) from plants raised from seed collected near Peking by Père David and sent by him to the Paris Museum in 1863. But the plant, from an English nursery, figured in Bot. Mag., t. 4269 (Vol. 72, 1846) appears to belong to this variety; its provenance is unknown. The other form of the species figured in the Botanical Magazine (t. 6801) is the one that Decaisne described as C. hookeri and is presented under the name C. tubulosa var. hookeri (Decne.) Hook. f. The figure shows a plant with mauve flowers (light blue in t. 4269) but the characters by which Decaisne differentiated his C. hookeri were the herbaceous stems and precocious flowers, no mention being made of flower colour. The plant figured was received from the Segrez Arboretum and probably raised from seed sent by Père David.
Clematis ‘Campanile’ and ‘Côte D’Azur’ are very near to C. heracleifolia but are said to be seedlings of C. × jouiniana, its hybrid with C. vitalba. Both have flowers of azure blue, and self-supporting stems, but in the latter the flowers are of a deeper shade and the leaves glossier. Clematis ‘Crépuscule’ is a hybrid between C. heracleifolia and C. stans, raised by Lemoine.