Clematis × eriostemon Decne.
C. × eriostemon is the first name to be published for a hybrid between C. integrifolia and C. viticella. The typical form of the cross was raised in France and described in 1852, but is probably not in cultivation over here. Better known is:
cv. ‘Hendersonii’. – This form was raised by Henderson of St John’s Wood about 1830, and is one of the most beautiful garden clematises. It is, however, scarcely woody enough to justify its inclusion in this work, dying back to the ground level each winter. The stems are slender, 6 to 8 ft high, the leaves pinnate, and the solitary, slightly perfumed flowers 2 to 21⁄2 in. across, deep bluish purple, and borne on stalks 3 to 4 in. long. Sepals four, spreading 3⁄4 in. wide. This clematis flowers most profusely from July to September, and if grown in a group, with the stems supported by stakes, makes a very gay display. The parentage of the plant as given above is deduced from its appearance, the habit and foliage resembling C. viticella, whilst the flower and feathery-tailed seed-vessel are those of C. integrifolia – a well-known herbaceous species.
cv. ‘Intermedia’. – This form of the cross is very handsome also, but taking more after C. integrifolia than ‘Hendersonii’ does. The flowers are bluish purple, 21⁄2 in. across, and appear from July to September. The plant is sturdier and shorter than ‘Hendersonii’.