Robinia hispida
Credits
Article from Bean's Trees and Shrubs Hardy in the British Isles
Recommended citation
'Robinia hispida' from the website Trees and Shrubs Online (treesandshrubsonline.
Common Names
- Rose Acacia
A deciduous unarmed shrub 6 to 8 ft high, of lax, rather gaunt habit, spreading by means of underground suckers, the branches covered with gland-tipped bristles 1⁄6 in. long. Leaves pinnate, 6 to 10 in. long; leaflets seven to thirteen, each 11⁄2 to 21⁄2 in. long, and from 3⁄4 to 11⁄2 in. wide, oval or ovate with a short bristle-like tip, very dark green; stalk hairy. Racemes 2 or 3 in. long, nearly as much wide, carrying five to ten flowers. The flowers are the largest and most showy among robinias, each about 11⁄4 in. long, with the rounded standard petal as much across, of a lovely deep rose; calyx 1⁄2 to 2⁄3 in. long, with long, slender, awl-shaped teeth, and bristly like the flower-stalk. Pods 11⁄2 to 21⁄2 in. long, 1⁄3 in. wide, thickly covered with gland-tipped bristles. Blossoms in May and June. Bot. Mag., t. 311.
Native of the south-eastern United States; introduced in 1743. In the wild it spreads and renews itself by means of sucker-growths extending several feet in a single season, but in cultivation it is usually grafted as a standard on R. pseudacacia so as to form a low, bushy-headed tree. Undoubtedly one of the loveliest of all trees of that character, it is, unfortunately, very liable to lose its branches during storms, owing to the brittle nature of its wood. For this reason a secluded spot is desirable for it. A remarkable fact in connection with this tree is the rarity with which it produces seed. It has probably never borne pods in this country, and even in the wild they are very seldom seen. The pods in the Kew Herbarium are three contributed by T. Meehan of Philadelphia, to whom they had been sent in response to inquiries made in a public journal. He himself had made diligent search for seed-pods on the mountains of Tennessee, where the shrub grows in great abundance, but never found any. The defect seems to be in the male part of the flower, and due to the absence of pollen.
'Macrophylla'
This is distinguished chiefly by the branches and leaf-stalks being nearly or quite free of bristles. The stalks of the racemes and flowers are hairy, but by no means as markedly as in the type. The flowers are even larger and more brightly coloured, the leaflets rounder (R. macrophylla Hort.; R. hispida var. macrophylla DC.; R. h. f. inermis Kirchn.).'Monument'
A compact shrub to 10 or 12 ft high, with rosy lilac flowers. Raised in the USA from var. fertilis, which it resembles in foliage. Also known as R. fertilis ‘Monument’.var. fertilis (Ashe) Clausen
Synonyms
Robinia fertilis Ashe
Leaflets relatively narrower, elliptic or oblong-ovate, often acute, downy beneath. A more important difference is that this variety sets fertile seed. A parent of ‘Monument’, see below.
var. kelseyi (Cowell ex Hutch.) Isely
Synonyms
Robinia kelseyi Cowell Ex Hutch.
Editorial Note
Treated by Bean at species rank, but now included by most authorities in a broadly conceived R. hispida, either in full synonymy (e.g. POWO 2025) or as one of several varieties (e.g. Flora of North America (Lavin & Lammers 2023)). The status of var. kelseyi as a naturally occurring variety is dubious, extensive searches in its supposed locality in Tennessee having found no plants, on which grounds Iseley (1998) concluded it is of likely horticultural (possibly hybrid) origin.
A lax-habited, deciduous shrub or small tree, with glabrous, slender branches. Leaves pinnate, 4 to 6 in. long; leaflets nine or eleven, oblong to ovate, 1 to 2 in. long, 1⁄3 to 5⁄8 in. wide, pointed, glabrous. Flowers brightly rose-coloured, in small clusters at the base of the young twigs; these clusters are sometimes simple racemes of three to eight flowers, but they are frequently forked or triplicate, the stalks always covered with glandular hairs. Each flower is 3⁄4 to 1 in. long, with a rounded standard petal 3⁄4 in. across; calyx 1⁄4 in. long, glandular-hairy, teeth narrow, awl-shaped. Pods 2 in. long, 1⁄3 in. wide, covered with reddish gland-tipped bristles 1⁄6 in. long. Bot. Mag., t. 8213.
The origin of this beautiful robinia is not definitely known. It was put into commerce about 1901, by Mr Harlan P. Kelsey, of Boston, USA, who informs me in a letter that it was ‘discovered in our nursery apparently growing spontaneously. We thought at first it was a cross between R. hispida and R. pseudacacia, but now we think it is a true species that has crept into the collections from the southern Allegheny Mountains.’ It was introduced to Kew in 1903, and is certainly one of the most beautiful shrubs added to gardens in recent years. The flowers appear in great profusion in June, and they are followed by handsome red pods. Its affinity with R. hispida, especially the smooth-branched form, is apparent, but it is abundantly distinct. Judging by its behaviour at Kew it can be made into a small tree, but it is very brittle. Increase is easily effected by grafting on roots of R. pseudacacia in spring.
R × slavinii RehdThis hybrid originated from seed of R. kelseyi collected by B. H. Slavin in 1914 in the Durand-Eastman Park, Rochester, N.Y., the pollen parent being R. pseudacacia. The flowers are rosy pink, more numerous in the raceme than those of R. kelseyi; the hairs of the inflorescence are eglandular and the pod is roughened by small warts. The leaflets are relatively broader, up to {7/8} in. wide.The same hybrid was raised by Messrs Hillier and named ‘Hillieri’ in 1933. It makes a small, round-headed tree, with lilac-pink flowers in June, borne freely even on young plants. A.M. 1962.
var. nana (Elliott) DC
Synonyms
Robinia elliottii (Chapm.) Ashe
Robinia nana Elliott
Editorial Note
Treated by Bean as R. elliottii, and placed in full synonymy with R. hispida by POWO (16/9/2025). Pending a full, revised account of the genus, we follow Isely (1998), who treats the taxon at varietal rank within R. hispida.
This is one of the dwarfest of the robinias, its maximum height being given as about 6 ft. Its stems are erect wands with a few short stout branches near the top; young shoots grey with down. There are eleven to fifteen leaflets to a leaf, which are oval, 1⁄2 to 1 in. long, grey-downy beneath. Flowers rose-purple or purple and white, nearly 1 in. long, produced in racemes five to ten together; flower-stalks and calyx grey-downy. Pods bristly. Blooms in May and June.
Synonyms
Robinia elliottii (Chapm.) Ashe
Robinia nana Elliott
Editorial Note
Treated by Bean as R. elliottii, and placed in full synonymy with R. hispida by POWO (16/9/2025). Pending a full, revised account of the genus, we follow Isely (1998), who treats the taxon at varietal rank within R. hispida.
This is one of the dwarfest of the robinias, its maximum height being given as about 6 ft. Its stems are erect wands with a few short stout branches near the top; young shoots grey with down. There are eleven to fifteen leaflets to a leaf, which are oval, 1⁄2 to 1 in. long, grey-downy beneath. Flowers rose-purple or purple and white, nearly 1 in. long, produced in racemes five to ten together; flower-stalks and calyx grey-downy. Pods bristly. Blooms in May and June.
Native of the S.E. United States from N. Carolina to Georgia, chiefly near the coast. Like R. boyntonii it has been grown as “R. hispida rosea”, but that species differs in not having the grey down on the young shoots, leaves, flower-stalks, and calyx which makes R. elliottii so distinct.
var. rosea Pursh
Common Names
Boynton Acacia
Synonyms
Robinia macrophylla G. Don, not DC.
Robinia boyntonii Ashe
Editorial Note
Treated by Bean as R. boyntonii, and placed in full synonymy with R. hispida by POWO (16/9/2025). Pending a full, revised account of the genus, we follow Isely (1998), who treats the taxon at varietal rank within R. hispida.
A deciduous shrub up to 10 ft high; young shoots unarmed, glabrous or very finely downy. Leaves 6 to 10 in. long, consisting of seven to thirteen leaflets which are oblong, blunt or pointed, 1 to 2 in. long, 1⁄2 to 1 in. wide, glabrous or soon becoming so. Flowers six to twelve together in loose racemes 21⁄2 to 31⁄2 in. long, produced from the lower leaf-axils of the young shoots in May and June, each flower barely 1 in. long; standard petal 3⁄4 to 1 in. wide; calyx 1⁄4 in. wide, bristly. The colour is described by Ashe as ‘rose-purple, pink, or purple and pink on the outer portion, white or much paler at the base’. Pods glandular-bristly.
Native of the E. United States from N. Carolina and Tennessee to Georgia and Alabama. It may have been introduced long ago and grown under the name “R. hispida rosea”, but the plant definitely named R. boyntonii by Ashe reached Kew in 1919. It is, however, not in cultivation at Kew at present. Ashe separates it from typical R. hispida ‘by its greater size, more oblong leaflets, many-flowered racemes, short calyx-lobes and smoothness’. The young shoots of that species are, of course, very bristly.