# The Trees of Great Britain & Ireland/Volume 2/Pterocarya

The Trees of Great Britain & Ireland was a multi-volume work, privately published between 1906 and 1913. The second volume was published 1907. The plates of this volume are part of the volume
PTEROCARYA
    Pterocarya, Kunth, Ann. Sc. Nat., sér. 1. ii. 345 (1824), Bentham et Hooker, Gen. Pl. iii. 399 (1880).
Deciduous trees belonging to the order Juglandeæ, with large, alternate, compound, imparipinnate leaves; leaflets serrate; stipules absent. Buds scaly or naked, the lateral ones often multiple, two to three in a vertical row above the insertion of the leaf. Pith chambered. Flowers monœcious, numerous in long pendent catkins. Male catkins usually several, arising singly in the leaf axils; in some species (caucasica, stenoptera) lateral on the preceding year's shoots, with an occasional catkin on the current year's shoot; in other species (rhoifola, Paliurus) all on the new shoots. Stamens nine to eighteen in several series on the axis of a three- to six-lobed scale, to which a bract is adnate on the back, the scale representing two bracteoles and one to four perianth segments. Female catkins solitary, terminating the young shoot. Female flowers with a bract and two bracteoles at the base; perianth four-lobed, adnate to the ovary, which contains one ovule, and is surmounted by a short style, divided above into two papillose stigmatic divisions. Fruit catkins long, with numerous nut-like fruits, which have in most species two lateral wings, in one species a single orbicular wing all round, due to the enlarged bracteoles of the flower, the bract persisting little changed at the base of the fruit. Nutlet, with a thin pericarp and a hardened endocarp, the latter divided below into four imperfect cells, and containing one seed, which is four-lobed below. Cotyledons bi-partite, each division being again deeply divided, forming four linear segments; carried above ground in germination.
Pterocarya and Juglans have similar foliage, and agree in the chambered pith of the twigs. They are readily distinguished when in fruit, that of Pterocarya being always small and winged. When specimens in leaf only are obtainable, the best mark of distinction lies in the buds, which in Pterocarya are either without scales or are enclosed in a long conical beaked funnel-like covering, composed of membranous scales—differing in either case from the short buds of Juglans with two to three external scales,
Seven species of Pterocarya are known, occurring in Persia, the Caucasus, China, Tonking, and Japan. A hybrid species has been obtained in cultivation, which will be described under P. caucasica. The seven species which occur in the wild state may be arranged as follows:—
1. Pterocarya Paliurus, Batalin, Act. Hort. Petrop. xiii. 101 (1892); Franchet, loc. cit.; J.H. Veitch in Journ. R. Hort. Soc. 1903, xxviii. 65, fig. 26. China: mountains of Szechwan, Hupeh, and Chekiang.
Section II. Diptera (Sectio nova).
* Buds naked, without scales.
2. Pterocarya stenoptera, C. DC. China, Tonking.
3. Pterocarya hupehensis, Skan, Journ. Linn. Soc. (Bot.), xxvi. 493 (1899). China: mountains of Hupeh.
4. Pterocarya Delavayi, Franchet, Journ. de Bot. 1898, p. 317. China: mountains of Yunnan.
5. Pterocarya caucasica, C.A. Meyer. Persia, the Caucasus.
6. Pterocarya macroptera, Batalin, Act. Hort. Petrop. xiii. 100 (1893). China: mountains of Kansuh.
7. Pterocarya rhoifolia, Siebold et Zuccarini. Japan.
PTEROCARYA CAUCASICA
    Pterocarya caucasica, C.A. Meyer, Verz. Pflanzen Caucasus, 134 (1831); Loudon, Arb. et Frut. Brit. iii. 1452 (1838).
    Pterocarya fraxinifolia, Spach, Hist. Nat. Veg. ii. 180 (1834); Lavallée, Arb. Segrez. Icones. 73, t. 21 (1885).
    Pterocarya Spachiana, Lavallée, op. cit. 69, t. 20.
    Pterocarya sorbifolia, Dippel (non S. et Z.), Laubholzk. ii. 327 (1892).
    Juglans fraxinifolium, Lamarck, Encyc. Meth. iv. 502 (1797).
    Juglans pterocarpa, Michaux, Fl. Bor. Am. ii. 192 (1803).
    Rhus obscura, Bieberstein, Fl. Taur. Cauc. i. 243 (1808).
A tree attaining 100 feet in height and ro feet or more in girth, usually however smaller, and tending to branch into several stems at no great height above the ground. Bark dark grey and furrowed. Shoots glabrous. Leaves (Plate 125, fig. 1) 16 to 20 inches long, ona stalk 2 to 3 inches long, only slightly swollen at its base; rachis not winged. Leaflets fifteen to twenty-seven, opposite or subopposite, sessile or sub-sessile, 3 to 5 inches long; oblong or oblong-lanceolate; acute, acuminate, or obtuse at the apex; unequal and rounded or narrowed at the base; dark green above; under surface lighter green, without glands, glabrous except for some stellate pubescence along the nerves and in their axils; thin in texture; sharply and finely serrate. Staminate catkins several, each in the axil of a leaf-scar on the preceding year's shoot, rarely one or more on the current year's shoot; scale usually five-lobed, stamens twelve to fifteen. Fruiting catkins up to eighteen inches long. ​Fruit ½ inch broad; wings semi-orbicular, concave below, conspicuously veined; nutlet with beaked apex.
Seedling.—The caulicle terete, erect, and about two inches in length, raises the two cotyledons well above the ground. Each cotyledon is shortly stalked, about an inch in width, and deeply bipartite, the two primary divisions being again divided for nearly two-thirds of their length, the whole forming four linear-oblong obtuse diverging segments. The cotyledons are palmately five-nerved at the base, the three middle nerves each ending at the base of a sinus and sending divisions into the segments. The young stem is slightly glandular near the apex. The first five leaves are alternate, simple, lanceolate or ovate, rounded at the base, acute or acuminate at the apex, penni-nerved, serrate, and vary in length from 1 to 2 inches, Succeeding leaves are compound, unequally pinnate, and with many leaflets.
Identification
In summer this tree is only liable to be confused with Pterocarya rhoifolia, which has scaly buds. It is distinguished from all species of Juglans by its naked buds.
In winter the following characters are available:—Twigs stout, olive green, glabrous except at the minutely pubescent, glandular tip. Leaf-scars oblique on the twigs, their lower part projecting, large, obcordate, marked by three crescentic prominences, which are the fused cicatrices of the vascular bundles. Pith pentagonal in cross section, chambered in longitudinal section. Buds without covering scales, consisting of a short shoot and three to four undeveloped leaves, which are stalked below, enlarged and lobed above, rusty brown in colour, minutely pubescent and glandular. Lateral buds multiple, two to three superposed vertically above each leaf-scar; the uppermost one like the terminal bud, but smaller and stalked; the lowermost close to the upper margin of the leaf-scar, minute and rudimentary.
Variety and Hybrid
1. Var. dumosa, Schneider, Laubholzkunde, 94 (1904); Pterocarya dumosa, Lavallée, Arb. Segrez. 217 (1877). This is a shrubby form, with yellowish brown twigs, and small closely-set leaflets, about 2½ inches long. The fruit and flowers are unknown; but it is probably a horticultural variety of P. caucasica.
2. Pterocarya Rehderiana, Schneider, op. cit. 93. This is a hybrid between P. caucasica and P. stenoptera, which was described by Rehder in Mitth. Deut. Dendrol. Gesell. 1903, p. 116. It grows in the arboretum at Segrez; and plants of it are now cultivated in the Arnold Arboretum, Massachusetts, where it is perfectly hardy. It is intermediate in character between the two species. The leaflets in texture, serration, etc., resemble those of P. caucasica, being a trifle smaller; but ​the rachis shows here and there a very slight wing, like that of P. stenoptera, only never serrate in margin. The fruits have oval wings, shorter and broader than those of P. stenoptera, the nut being more beaked than in that species. The veining of the fruit-wings resembles P. caucasica.
Distribution
Pterocarya caucasica has been found in the northern provinces (Astrabad and Ghilan) of Persia, and in Russian Armenia, as well as in the Caucasus. According to Radde, it occurs in the marshy delta of the Rion in company with Alnus glutinosa, and along the coast of the Black Sea, mixed with oak, beech, and hornbeam. It grows sometimes as a tree, but oftener as a tall shrub, on the banks of streams. It extends up to about 1200 feet only in Kachetia, and is met with as far eastward as Talysch, on the coast of the Caspian Sea, where in damp places it forms the principal underwood. It is not found wild in the interval between the lower Rion on the west and the lower valley of the Alazan on the south side of the central Caucasus, and is again absent from here to the province of Talysch.
Mr. Younitsky of the Russian Forest Service has kindly sent me the following account of the tree in the Caucasus. He says it is only found in certain stations, rarely over 1200 feet elevation, and always in moist or very wet places, to which it is better adapted than even the alder. In the young stage the tree is very delicate and susceptible to spring frosts, requiring shelter when young; and when older does not bear shade well. Very large trees occur, of 100 feet in height and 10 feet in girth, and logs of it are obtained bare of branches for 50 feet, with a girth of 5 feet at the smaller end. It grows very rapidly in youth, making a height of 30 feet in ten years. The wood is light and soft, resembling much that of the lime-tree, and is chiefly used for making boxes and packing-cases. The bark is used for sandals and roofing. The leaves contain a poisonous matter, and when thrown into water intoxicate the fish, which rise to the surface and are easily caught. The tree is rarely cultivated, but is recommended for planting in the wettest situations, where it will thrive better than almost any other tree.
Cultivation
Pterocarya caucasica was introduced into France by the elder Michaux on his return from Persia in 1782. According to Bosc the first tree was planted at Versailles, others a little time after being planted about the Museum in Paris. According to Mouillefert, there are still growing at the Trianon, Versailles, and at the Museum, Paris, two fine specimens which are probably original trees. The tree flowered and produced fruit in 1826 in the park at Malesherbes, according to a note by Gay in the Kew Herbarium. There is a tree 80 feet high and g feet in girth in the Old Botanic Garden at Geneva, which was seen by Elwes in 1905.
Plate 121.
PTEROCARYA CAUCASICA AT MELBURY
Plate 122.
PTEROCARYA CAUCASICA AT CLAREMONT
I have raised numerous plants of Pterocarya from seed sent me from the Caucasus by the late Dr. Radde in 1903, some of which was distributed by the Royal Horticultural Society. The seedlings grow fast, attaining 2 feet or more in height at two years old, but do not ripen their wood well when young, and are extremely liable to be injured by frost if not protected in spring. The leaves appear about the same time as those of Liriodendron. The tree does not seem to dislike lime in the soil, and should be planted out when 3 or 4 feet high, in a situation where the ground is not liable to drought in summer, or near running water.
Remarkable Trees
This is one of the most ornamental hardwoods that we have; and is well worth planting in warm and sheltered positions in the south of England, where it thrives from Kent to Devonshire.
By far the largest and finest tree of this species known in England is at Melbury, Dorsetshire, the seat of the Earl of Ilchester. This magnificent tree (Plate 121) is growing on a sheltered bank below the house, on soil which contains lime, close to the finest specimen I know of Picea Morinda. It is no less than go feet high by 11 feet in girth, and has a straight clean bole about 15 feet long, spreading out into a symmetrical head of branches, and when I saw it in September 1906 had many catkins of fruit hanging on it.
Its spreading habit is shown by a fine tree at Claremont Park, near Esher, Surrey, which grows on deep sandy soil, and is a noble ornament of a lawn. The illustration of this tree (Plate 122) is from a photograph taken in 1903, when it measured about 50 feet in height, with a bole of only 4 feet high but no less than 18 feet in girth. It divides into eight large limbs, each of which is about 4 feet in girth, and the foliage spreads over an area of 30 yards in diameter. The tree is believed by Mr. Burrell, the gardener, to be about eighty years old, and seems to be decaying at the heart. The bark is very rough and deeply furrowed, and the leaves and flower-buds were just appearing, after a very mild winter, on 6th March. A self-sown seedling from it was about 2 feet high.
Another fine tree is growing at Tortworth Court, from which I gathered ripe seed in October 1900, one of which grew in the following spring. The Earl of Ducie has raised several young trees from the same parent in other seasons. At Linton Park, Kent, there is a fine tree, which was about 50 feet high in September 1902, but not so large as the one at Claremont. Ripe fruiting specimens were sent from Devonshire by Sir John Walrond in 1888, which were figured by ​Dr. Masters in the Gardeners' Chronicle, but I have been unable to procure particulars of the tree from which the specimens were obtained.
In the Botanic Garden, Cambridge, there is an old tree which was 58 feet high in 1903, with eight stems, girthing from 3 feet to 4 feet 3 inches; and from the roots of another tree which was blown down about 1885 a number of strong stems, about twenty, have sprung up, which average about 50 feet in height and 24 feet in girth. These particulars, which have been kindly sent me by Mr. Lynch, the curator, show the remarkable power of the tree in producing root-suckers (Plate 123).
A tree at Fota, near Queenstown in Ireland, seen by Henry in 1903, measured 42 feet high by 3 feet 9 inches in girth. It produced flowers and fruit in 1902.
Dr. Masters recommends it for planting in towns, and says that there was a good specimen in the Chelsea Botanic Garden (since cut down) in 1891. There are said to be good specimens in some of the towns in Holland. (H.J.E.)
PTEROCARYA RHOIFOLIA
    Pterocarya rhoifolia, Siebold et Zuccarini, Abh. Bayr. Ak. Wiss. Math. Phys. Kl. iv. 2, 141 (1845); Maximowicz, Mél. Biol. viii. 637 (1872); Shirasawa, Icon. Ess. For. Japon. text 35, t. 16 (1900).
    Pterocarya sorbifolia, Siebold et Zuccarini, loc. cit.; Rehder, Mitt. Dendrol. Deut. Gesell. 1903, p. 115.
A tree attaining, according to Shirasawa, 100 feet in height, with a straight stem Io feet in girth. Bark greyish brown with deep longitudinal fissures. Shoots glabrous. Leaves (Plate 125, fig. 3) 8 to 16 inches long, on a stalk about 2 inches long, which is swollen at its insertion; rachis without wings. Leaflets, fifteen to twenty-one, usually opposite, sessile or sub-sessile, 2½ to 5 inches long, oblonglanceolate, acuminate at the apex, unequal at the base, which is rounded or somewhat narrowed; dark green above; under surface lighter green, with glandular scales, and some tomentum on the midrib and nerves and in their axils; somewhat thicker in texture than the leaves of P. caucasica; margin sharply and finely serrate.
Flowers appearing with the leaves. Staminate catkins two to three at the base of the young shoots; scale three-lobed, pubescent, bearing nine to twelve short-stalked stamens. Pistillate catkins, solitary, terminal at the end of the young shoot, later apparently lateral owing to the growth of the upper axillary bud. Fruiting catkins, 8 to 10 inches long; fruit an inch across; nut with a short, scarcely beaked apex; wings rhombic, broader than long, without any hollow at their base, inconspicuously veined.
The above description applies to the glabrous form, which is in cultivation in England and is common in Japan. In wild specimens from Yezo the leaves appear to be much more pubescent, the rachis and nerves being often covered with dense long hairs.
Plate 123.
PTEROCARYA CAUCASICA AT CAMBRIDGE
In Japan this is a large tree known as Sawa gurumi, which I saw in the central provinces of Hondo, where it grows to a height of 50 to 60 feet, old trees attaining a girth of 8 or ro feet. It generally grows on the banks of streams in mixed forest, and did not seem to be very common or to be valued for its timber, though I got a specimen of the wood from the Government sawmills at Atera, which is now at Kew.
Sargent found it very abundant on the slopes of Mt. Hakkoda, in the north of Hondo, at 2500 to 4000 feet elevation, where it attains as much as 80 feet in height, being next to the beech the largest deciduous tree in the forest. It is a broadtopped tree with stout spreading branches, and when covered with its long hanging slender racemes of fruit, is very handsome. It is hardy at the Arnold Arboretum near Boston and produces seeds there.
Pterocarya rhoifolia is recorded by Diels as having been collected by Von Rosthorn in the province of Szechuan in China.
It seems to have been introduced into cultivation by the Duke of Bedford, to whom seeds were sent from Japan in 1889. Young plants from some of this seed were raised at Kew in 1890; and these have now attained about 12 feet in height. They are the only specimens we have seen in England. (H.J.E.)
PTEROCARYA STENOPTERA
    Pterocarya stenoptera, C. de Candolle, Ann. Sc. Nat. sér. IV. xviii. 34 (1862); Lavallée, Arb. Segrez. Icones, 65, t. 19 (1885); Franchet, Journ. de Bot. 1898, p. 317.
A tree, 50 to 60 feet in height, with a girth of stem of 6 or 8 feet. Bark rough. Leaves (Plate 125, fig. 2) about a foot in length; rachis covered with bristles, slightly swollen at its insertion, and having on each side a conspicuous irregular membranous wing, occasionally slightly serrate in margin. Leaflets nine to twenty-five, opposite or alternate, terminal leaflet often wanting; coriaceous; under surface with a few scattered glands, and some pubescence on the midrib and nerves and in their axils; oblong or oblong-lanceolate; acute at the apex, unequal and rounded or narrowed at the base, finely and sharply serrate in margin, 3 to ​inches long. Male catkins, arising as in P. stenoptera; scale glandular, four-lobed; stamens six to ten. Female catkins 8 inches long; bract minute, bracteoles oblong and longer than the style, perianth with four subulate lobes, Fruit: catkins a foot or more in length; nut with conic beak-like apex; wings linear-oblong and erect,
The above description applies to the form in cultivation, which is also common in the wild state. The species is, however, very variable as regards the amount of pubescence, the twigs being often glabrous and the leaf-rachis only slightly pubescent. In many wild specimens the wing of the rachis is very slight.
This species is readily distinguishable in summer by the winged rachis of the leaf. In winter the twigs are slender and covered with a rusty-red bristly pubescence; but in other respects resemble those of P. caucasica. The buds, more slender than in that species, but similar in structure and position, are greyish in colour.
This is a common tree in the central and southern provinces of China, extending in a slightly different form into Tonking. It is usually met with in the plains and low hills, along rivers and water-courses; and never grows to be a large tree. It is recorded from near Moukden in Manchuria, where it was collected by James; but was probably only cultivated there. It is usually called ma-liu by the Chinese; and is much planted in the streets of Shanghai, where it is often called "Chinese ash" by the European inhabitants. As the climate of the regions where it grows naturally is very different from that of England, it is liable to be injured by spring frosts, and fails from want of heat in autumn to ripen its wood. The timber is considered in China to be of little value.
The tree was introduced into Europe apparently by Lavallée, who received the seeds from Siebold, about 1860. It supported at Segrez very low temperatures in 1870 and 1871; but succumbed during the severe winter of 1879-1880. Lavallée considered it to be about as hardy as the common walnut.
The only specimen that we have seen in England of any size is at Tortworth, where Elwes measured in 1905 a tree 32 feet high by 2 feet 3 inches in girth, believed by Lord Ducie to have been planted about twenty years. It is in a shady and sheltered valley and produced small racemes of fruit in 1905. (A.H.)
* ↑ Cf. Lubbock, Seedlings, ii. 521, fig. 662 (1892).
* ↑ Two seedlings were raised by Elwes from seeds of this tree, one of which is now about eighteen inches high, and shows evidence of its hybrid origin in the leaves.
* ↑ Radde, Pfanzenverbreitung in Kaukasusländern, 109, 139, 159, 182, 205, etc.
* ↑ Traité des Arbres, ii, 1195 (1898).
* ↑ I could not find either of these trees in 1905.—H.J.E.
* ↑ The severe frost of 20th–22nd May 1905 seriously injured all my young trees, and it is evident that this tree should only be planted in situations where spring frosts are not severe.
* ↑ Mr. Burrell found a seedling in the summer of 1899. See Garden, 1902, lxii. 234, where a figure and description of the tree are given. See also Garden, 1894, xlv. 404, fig., and Gard. Chron. 1894, xvi. 192. According to a note in the Kew Herbarium, the Claremont tree was, in 1887, 45 feet high by 13½ feet in girth.
* ↑ Journ. R. Hort. Soc. 1891, xiii. 86.
* ↑ Flora von Central China, 274 (1901).
* ↑ Var. tonkinensis, Franchet, Journ. de Bot. 1898, p. 318. A geographical form, distinguished by large leaflets, up to 6 inches long, and linear wings to the fruit, which diverge at a wide angle.
* ↑ Henry, 'Chinese Names of Plants," Journ. China Branch R. Asiat. Soc. xxii. 256 (1887).