A round-topped, deciduous tree 30 to 50 ft high, with thick, stiff branches and rather open habit; all the parts more or less downy. Leaves opposite, the small ones ovate, the larger ones three- to five-lobed, the lobes pointed but shallow, the base deeply notched, the dimensions are very variable; in adult trees they are 5 to 10 in. long and wide, dark green, and with scattered hairs above, covered beneath with a soft, greyish wool; stalk nearly as long as the blade. Panicle terminal, up to 1 ft long, the flowers forming in autumn but not opening until the following May. Corolla blue-purple, fragrant, 11⁄2 to 2 in. long, shaped like a huge foxglove; calyx woolly, 1⁄2 in. long, bell-shaped, with five ovate teeth. Seed-vessel an ovoid, pointed capsule, 11⁄2 to 2 in. long, containing numerous winged seeds.
Native of China, but introduced from Japan to France in 1834 by means of seeds given to Neumann, director of the hothouses at the Jardin des Plantes, Paris. Only one plant was raised, which was 12 ft high in 1840 and flowered in the following year. In 1842 it was estimated that the total stock of plants raised from this single individual by seeds and vegetative propagation was between 20,000 and 30,000. There was a direct importation of seeds from Japan to Britain in 1838, which was distributed to private gardens, but some at least of the plants distributed commercially came from the Paris tree. In 1843, F. and A. Smith of Hackney were asking 7s 6d each for plants in 3-in. pots, a moderate price for a novelty (Gard. Chron. (1843), p. 81). It first flowered at Hampton Court in 1846 or 1847, and the first general flowering in Britain was in 1858 (Gard. Chron. (1849), pp. 387 and 405; op. cit., 1858, many references).
Few more beautiful flowering trees than this exist, but although the tree is fairly hardy and sets its flowers, they often do not develop in this country, owing to its curious habit of exposing them in bud through the winter. Perhaps they do not derive sufficient stamina from our dull summers, but more likely the unrest of our winters, with their alternate frosts and mild spells, prevents their proper development.
But whilst many gardens in Great Britain are denied the blossoms of this tree, it may, by another mode of cultivation, be made to provide a fine feature anywhere but in the coldest parts. This is to treat it simply as a fine-foliaged plant. To get the best effect the plants should be set out 3 or 4 ft apart in a group of at least twenty, and be kept to a single stem, the object being to obtain leaves as large as possible. In spring the stem is cut back to within 2 in. of the older wood. From the crowd of young growths that then push out the two strongest are selected, the rest rubbed off. Two are left for fear of accident only, and after they are fairly established the weaker one is removed. It then only remains to water when necessary and to feed the plants with manure. Well-grown plants will have huge pentagonal leaves 2 to 3 ft across, and the sturdy erect stems will grow over 12 ft high in the season. Paulownias need a rich soil and are best propagated from seed, which is produced in plenty on the Continent. Root-cuttings may also be used. Young plants, being almost herbaceous, are very tender and should pass their first winter under glass.
The tree at Westonbirt mentioned below is by far the tallest paulownia so far recorded in Britain and one of the largest in girth. Other notable specimens are: Linton Park, Kent, 35 × 51⁄2 ft (1972); Botanic Gardens, Bath, 40 × 71⁄2 ft (1962); Paignton Zoo, Devon, 40 × 7 ft (1969); Hergest Croft, Heref., 38 × 31⁄2 ft (1969); Shelton Abbey, Co. Wicklow, Eire, 36 × 6 ft (1968); Birr Castle, Co. Offaly, Eire, 44 × 4 ft (1966).
An old paulownia at Ashridge Park, Herts., is portrayed in Gard. Chron., Jan. 26, 1957, p. 98. In the accompanying letter, Maynard Greville gave its dimensions as 56 × 73⁄4 ft. He also mentioned a tree at Elsenham Hall, Essex, 53⁄4 ft in girth, which had been completely bored out by woodpeckers to within 3 ft of the ground, but was still alive.
During his first expedition for the Arnold Arboretum in 1907-9, Wilson found P. tomentosa growing wild in W. Hupeh and sent seeds under W.769. This form was generally referred to as P. tomentosa var. lanata or as P. recurva and a note on a tree at Exbury under the former name will be found in Journ. R.H.S., Vol. 68 (1943), p. 235. There is no significant botanical difference between the Wilson introduction and the common form, but the plants are reported to have grown faster. Also, judging from the tree in the Specimen Avenue at Westonbirt raised from the Wilson sending, this form also grows taller; in 1972 it measured 86 × 63⁄4 ft, a remarkable height for this species, and is still in good health. H. J. Elwes had a tree from the Wilson seeds at Colesbourne, suckers of which he distributed to a number of gardens.