Styphnolobium japonicum
Credits
Article from Bean's Trees and Shrubs Hardy in the British Isles
Recommended citation
'Styphnolobium japonicum' from the website Trees and Shrubs Online (treesandshrubsonline.
Synonyms
- Sophora japonica L.
Editorial Note
Bean treated this species under the name Sophora japonica; the text below is updated to reflect the revised taxonomy – see also the genus entry for Styphnolobium.
A deciduous tree, 50 to 80 ft high, of rounded habit and branching low down when growing in the open, but capable of forming a tall clean trunk when close planted. Bark downy when young, glabrous later and dark greenish brown; on old trunks it is grey, and corrugated rather like an ash. Leaves rich green, pinnate, 6 to 10 in. long, composed of nine to fifteen leaflets, which are ovate or oval, 1 to 2 in. long, half as wide, covered with small appressed hairs beneath. Flowers in terminal panicles 6 to 10 in. long and wide, creamy white, each about 1⁄2 in. long; calyx 1⁄8 in. long, bell-shaped, green, shallowly toothed. Pods 2 to 31⁄2 in. long, glabrous, one- to six-seeded; rarely seen in Britain.
Native of China (not of Japan); introduced to France in 1747 and thence to England in 1753. It is one of the most beautiful of all leguminous trees, although it does not flower in a young state – not commencing until thirty to forty years of age. Old trees flower freely, especially after hot summers. The blossoms are not developed until September, and in wet cold summers do not develop at all. They do not fade on the tree, but drop off quite fresh, making the ground white beneath. On the continent of Europe, thanks to the warmer summers, it attains a larger size than with us, and frequently ripens seeds, which are the best means of increase. All parts of the plant, even the wood, contain a purgative principle said to be so potent that turners working on the green wood are immediately afflicted by colic, and that well-water becomes laxative if the leaves fall into it in autumn.
The largest specimen of S. japonicum recorded recently grows at Syon Park, London; it measures 76 × 151⁄4 ft at 4 ft (1967). Others are: University Parks, Oxford, 59 × 91⁄4 ft (1975); Aldenham House, Herts, 60 × 61⁄4 ft (1976); Angelsey Abbey, Cambs., 48 × 53⁄4 ft (1973); Penrhyn Castle, Bangor, 44 × 61⁄2 ft (1974). The decrepit tree at Kew in G.15 was planted soon after the introduction of the species and is kept for its historical interest.
Var. pubescens (Tausch) G.Kirchn., with downy leaves beneath, is no longer recognised as a distinct variety; it has been grown in gardens under the name Sophora korolkowii Dieck ex Koehne (syn. Sophora japonica var. pubescens (Tausch) Bosse, Sophora pubescens Tausch, Sophora japonica var. korolkowii Zab. ex Henry). Bean saw a notable specimen at the Arboretum at Segrez, France, in July 1904, covered with panicles of unexpanded flowers (described as dull white when open). Leaflets longer than in the species (fully 3 in.), but narrower in proportion, covered beneath with a very minute, close down. The young wood too is more downy, and of a lighter colour.
From the Supplement (Vol. V)
specimens: Syon House, London, in Wilderness near river, 88 × 161⁄4 ft at 4 ft (1982); University Parks, Oxford, 55 × 91⁄2 ft (1981); Angelsey Abbey, Cambs., pl. 1929, 60 × 71⁄4 ft (1984); Linton Park, Kent, 85 × 83⁄4 ft (1984); Nymans, Sussex, Magnolia Garden, 46 × 111⁄4 ft at 2 ft (1983); Kingsmere, Shawford, Hants, 75 × 91⁄4 ft (1977); Jephson Gardens, Leamington Spa, Warwicks., 45 × 9 ft (1981); Bath Botanic Garden, 38 × 4 ft (1978).
'Pendulum'
A very picturesque weeping tree with stiff, drooping branches. It should be grafted on stocks of the ordinary form 10 to 15 ft high. An admirable lawn tree, or for forming a natural arbour. It was distributed by Loddiges early in the 19th century, but whence he obtained it is unknown. Other pendulous forms are cultivated on the continent and may have originated there. Several were found among seedlings of a single sowing made at Paris in 1857 (Rev. Hort., 1861, p. 85).
'Variegatum'
Leaves margined with creamy white, but of little value.
'Violaceum'
This was introduced from China to the Jardin des Plantes at Paris about 1858. Its flowers, which appear later than those of the normal form have the wing-petals and keel stained with rose-violet (syn. Sophora japonica var. violacea Carrière; Sophora violacea Hort. ex Koehne). It has been cultivated at Kew for many years, but usually sets its flower-buds too late in the season to make a display. Except in colour it does not differ materially from the type. According to Henry the flowers of S. japonicum, as he saw them in China, vary a good deal in colour, some forms being white, others yellow.