Hydrangea aspera D. Don

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Credits

Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Hydrangea aspera' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/hydrangea/hydrangea-aspera/). Accessed 2019-12-10.

Genus

Synonyms

  • H. villosa Rehd.
  • H. aspera var. velutina Rehd.
  • H. aspera var. strigosior Diels
  • H. rehderana Schneid.
  • H. fulvescens Rehd.
  • H. kawakamii Hayata

Glossary

calyx
(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
herbarium
A collection of preserved plant specimens; also the building in which such specimens are housed.
inflorescence
Flower-bearing part of a plant; arrangement of flowers on the floral axis.
acuminate
Narrowing gradually to a point.
acute
Sharply pointed.
apex
(pl. apices) Tip. apical At the apex.
appressed
Lying flat against an object.
clone
Organism arising via vegetative or asexual reproduction.
convex
Having a rounded surface.
corymb
Unbranched inflorescence with lateral flowers the pedicels of which are of different lengths making the inflorescence appear flat-topped.
cuneate
Wedge-shaped.
entire
With an unbroken margin.
herbarium
A collection of preserved plant specimens; also the building in which such specimens are housed.
hybrid
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
indumentum
A covering of hairs or scales.
lanceolate
Lance-shaped; broadest in middle tapering to point.
midrib
midveinCentral and principal vein in a leaf.
ovary
Lowest part of the carpel containing the ovules; later developing into the fruit.
ovate
Egg-shaped; broadest towards the stem.
receptacle
Enlarged end of a flower stalk that bears floral parts; (in some Podocarpaceae) fleshy structure bearing a seed formed by fusion of lowermost seed scales and peduncle.
strigose
Bearing stiff hairs or bristles.
subspecies
(subsp.) Taxonomic rank for a group of organisms showing the principal characters of a species but with significant definable morphological differentiation. A subspecies occurs in populations that can occupy a distinct geographical range or habitat.
truncate
Appearing as if cut off.
variety
(var.) Taxonomic rank (varietas) grouping variants of a species with relatively minor differentiation in a few characters but occurring as recognisable populations. Often loosely used for rare minor variants more usefully ranked as forms.

References

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Credits

Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Hydrangea aspera' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/hydrangea/hydrangea-aspera/). Accessed 2019-12-10.

A deciduous shrub up to 12 ft high in cultivation, more in width, occasionally a small tree in the wild; young stems clad with short appressed hairs and/or longer more spreading hairs. Leaves mostly lanceolate to narrow-ovate, 4 to 10 in. long, 1 to 4 in. wide, acute or acuminate at the apex, cuneate to rounded at the base, sparsely hairy above, lower surface densely coated with soft, whitish, erect or spreading hairs, the midrib beneath sometimes with longer, brownish hairs, margins edged with forward-pointing or spreading teeth, which are sometimes reduced to threadlike projections; petioles 1 to 4 in. long, with hairs similar to those of the branchlets. Inflorescence a flat-topped or slightly convex cymose corymb up to 10 in. across, borne terminally on the season’s shoots but often supplemented by subsidiary clusters from the uppermost leaf-axils; in­florescence-axes with hairs similar to those of the branchlets. Receptacles of fertile flowers truncate at the apex, enclosing the ovary, usually purplish pink but sometimes uncoloured. Calyx very small. Petals five, coloured like the receptacle, soon falling. Stamens ten, blue. Styles two to four, blue. Ray- flowers variable in number, up to 1 in. across (occasionally wider); sepals mostly four, roundish, toothed or entire, varying in colour from white through pale pink to purple, the veins often more deeply coloured than the rest of the surface. Capsules hemispheric, 110 to 18 in. wide. Seeds tailed.

H. aspera was described in 1825 from a specimen collected in Nepal and ranges from there eastward to western and central China and Formosa; it also occurs in Java and Sumatra.

H. aspera varies somewhat in the size, shape, and toothing of its leaves, in the indumentum of the leaf-undersides, branchlets, etc., and in the colour of the flowers, though the variation is not so great as the large number of synonymous names might suggest. Mainly the species is represented in gardens by plants called H. villosa, which derive from seeds collected by Wilson during his two expeditions to western China for the Arnold Arboretum (some, perhaps, from seeds sent later by Forrest from Yunnan). The origin of the plants distributed as H. aspera or H. aspera var. macrophylla is not certain, but these too appear to be Chinese forms of the species.

In its best forms, H. aspera is a very beautiful species and all the more valuable for flowering after midsummer. It is, moreover, one of the few hydrangeas that really thrives in chalky soil; how well it does so is proved by the fine specimen in the chalkpit at Highdown in Sussex, which has produced numerous self-sown seedlings in its time. H. aspera is not, however, an easy plant to suit and is subject to damage by late spring frosts. It is said to succeed best in a dryish soil and should never be planted where the soil lies excessively wet in winter. Like many other hydrangeas, it is tender when young and should be given some protection during its first few winters.

H. aspera varies in its garden characters as well as botanically. Some plants agree with the type of H. villosa in having the ray-flowers bluish purple but they may be pink or white with pink veins There is also variation in flowering time, so that two or three selected plants could provide colour from July until September. A particularly fine form of H. aspera is grown at Westonbirt in Gloucestershire, with bold foliage and flower-heads 10 in. or more across. This clone appears to be sterile and it has been suggested that the original plant might have been a hybrid with H. sargentiana, though there is no sign of the influence of the latter species in the specimen seen. Similar plants are grown under the erroneous names H. aspera macrophylla or H. strigosa macrophylla (see further below under subsp. strigosa). On the other hand, some plants distributed under the name H. aspera are a poor form of the species, and it has been suggested that for this reason it would cause confusion if H. villosa were to be sunk in H. aspera. But this poor form, although still to be seen in collections, is probably not in commerce. Furthermore, the plants raised from the seeds collected by Wilson and grown under the name H. villosa are also very variable in ornamental value.

subsp. strigosa (Rehd.) McClintock H. strigosa Rehd.; H. aspera var. macrophylla Hemsl.; H. strigosa var. macrophylla (Hemsl.) Rehd. – This subspecies differs from the typical subspecies described above only in having the under-surface of the leaves covered with short, stiff, appressed hairs. It was introduced by Wilson when collecting for the Arnold Arboretum, and, from the details given in Plantae Wilsonianae, it would seem that the seeds were collected at a comparatively low altitude, which may explain why some of the plants in cultivation are not very hardy and tend to flower late in the season. One clone that has been distributed commercially develops its inflorescences so late that it has never flowered in Michael Haworth-Booth’s collection, except under glass. In the Gardeners’ Chronicle for October 19, 1935, Besant mentions a plant raised from Wilson 757 that regularly flowered in that month at the Glasnevin Botanic Garden, Dublin, and there is a plant at Rowallane in Northern Ireland which is also October-flowering and certainly belongs to the subsp. strigosa, judging from the specimen in the Wisley herbarium. However, this late flowering is certainly not a character of the subsp. strigosa as a whole. In the Kew Herbarium there are flowering specimens from garden plants taken in almost every month from June to October. A poor form of the subsp. trigosa, distributed under the erroneous name “H. longipes”, flowers in August.

The plant at Wakehurst Place, Sussex, from which a flowering branch is figured in Bot. Mag., t. 9324, was raised originally by H. J. Elwes from a stray in a packet of seeds of Decumaria sinensis, collected by Wilson during his second expedition for the Arnold Arboretum.

The subsp. strigosa is, or was, also in cultivation from Kingdon Ward’s No. 20940.

A specimen collected by Henry in China, and named H. aspera var. macrophylla by Hemsley, has the leaves strigose beneath and the variety was accordingly transferred to H. strigosa by Rehder. No doubt for this reason some garden plants called H. aspera macrophylla have been renamed H. strigosa macrophylla, although these plants, at least those examined, do not belong to the subsp. strigosa but to the typical subspccies. They are, in other words, H. aspera macrophylla of gardens, but not of Hemsley.

For H. aspera subsp. robusta see H. longipes; for H. aspera subsp. sargentiana see H. sargentiana.

From the Supplement (Vol. V)

The plants distributed in gardens as H. aspera macrophylla may well be all of one clone, for which ‘Macrophylla’ could be taken as a valid cultivar name, although it is not the H. aspera var. macrophylla of Hemsley. The leaves are notable for their size, being almost as large as those of H. sargentiana. Inflorescence 8 to 10 in. wide; fertile flowers purple, ray-flowers white tinged with lilac. It is very hardy and attains 6 ft or even more in height.


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