A natural hybrid between Q. imbricaria and Q. velutina, of which there are several fine trees in this country. The leaves in shape approach those of Q. imbricaria, being oblong and tapered at both ends; they are, however, rarely entire as in that species, but are more or less irregularly, and either deeply or shallowly lobed, 3 to 7 in. long, 1 to 21⁄2 in. wide; dark green and glossy above, furnished with a scurfy down beneath, but not so thickly as in Q. imbricaria. Young shoots more or less scurfy with starry down. This oak is named in honour of T. G. Lea, who discovered it about 1830, near Cincinnati, Ohio. According to Sargent, it is scattered widely as solitary individuals over the south-eastern United States. From the variable character of trees given this name, especially in shape and pubescence of leaf, it is probable that it represents trees of different origin, although Q. imbricaria is undoubtedly one parent. In 1910 I saw trees in the Arnold Arboretum with leaves 3 to 5 in. wide. It is always a vigorous, handsome oak.
The example at Kew in the Oak collection, pl. 1877, measures 64 × 6 ft (1964). Others on record are: Leonardslee, Sussex, 60 × 23⁄4 ft (1969); Highclere, Hants, 55 × 6 ft (1968); Westonbirt, Glos., 63 × 51⁄4 ft (1967).
Some other hybrids between a willow oak and a red oak may be mentioned here (see also Q. × ludoviciana):
Q. × heterophylla Michx. f. – A natural hybrid between Q. pbellos and Q. rubra (borealis). It is a vigorous tree which has attained in cultivation a height of over 80 ft and a girth of around 11 ft; buds glabrous or shortly downy. Leaves mostly 3 to 6 in. long, varying, even on the same tree, from entire to lobulate or lobed, the venation irregular, soon glabrous above, glabrous also beneath except for axillary tufts; petioles 1⁄2 to 1 in. long. Fruits, probably rarely produced in this country, intermediate between those of the parents.
This oak was described in 1812 from a tree growing on John Bartram’s property near Philadelphia, USA. The younger Michaux is believed to have collected acorns from it and sent them to France, so some of the cultivated trees may descend from the original type-tree. But the hybrid occurs elsewhere in the USA and may have arisen independently in cultivation also.
There is an example at Borde Hill, Sussex, which came from Rovelli’s nurseries as “Q. viridis” and was at first identified by an American botanist as Q × morehus and later as Q × heterophylla, which seems to be correct. It measures 56 × 6 ft (1967) and has more than doubled its girth in 22 years.
Q. × runcinata (A.DC.) Engelm. Q. rubra var. runcinata A.DC. – A hybrid between Q. rubra and Q. imbricaria. Leaves obovate-oblong in general outline, 4 to 6 in. long, 2 to 3 in. wide, some as deeply lobed as in Q. rubra, others less so, the lobes in three or four pairs, entire or sparsely toothed; undersurface with scattered rust-coloured hairs and with a few long hairs in the vein-axils; petiole up to 1 in. long. Fruits intermediate between those of the parents.
Q. × schochiana Dieck. – A hybrid between Q. phellos and Q. palustris. It occurs occasionally in the wild, but the original form arose at Wörlitz in Germany and was distributed by Dieck at the end of the last century. Probably all the plants cultivated in Europe descend from this. Leaves in their general shape resembling those of Q. phellos, but with the margins undulated, or with a few small, irregularly spaced lobes. There is an example in the Winkworth Arboretum measuring 30 × 21⁄2 ft (1969).