Acer campbellii J. D. Hooker & Thomson ex Hiern

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Credits

Dan Crowley (2020)

Recommended citation
Crowley, D. (2020), 'Acer campbellii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-campbellii/). Accessed 2020-10-28.

Genus

  • Acer
  • Section Palmata, Ser. Sinensia

Common Names

  • Campbell's Maple

Infraspecifics

Other species in genus

Glossary

asl
Above sea-level.
cordate
Heart-shaped (i.e. with two equal lobes at the base).
glabrous
Lacking hairs smooth. glabrescent Becoming hairless.
included
(botanical) Contained within another part or organ.
inflorescence
Flower-bearing part of a plant; arrangement of flowers on the floral axis.
key
(of fruit) Vernacular English term for winged samaras (as in e.g. Acer Fraxinus Ulmus)
ovary
Lowest part of the carpel containing the ovules; later developing into the fruit.
ovate
Egg-shaped; broadest towards the stem.
pubescent
Covered in hairs.
section
(sect.) Subdivision of a genus.
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.
synonym
(syn.) (botanical) An alternative or former name for a taxon usually considered to be invalid (often given in brackets). Synonyms arise when a taxon has been described more than once (the prior name usually being the one accepted as correct) or if an article of the International Code of Botanical Nomenclature has been contravened requiring the publishing of a new name. Developments in taxonomic thought may be reflected in an increasing list of synonyms as generic or specific concepts change over time.
taxon
(pl. taxa) Group of organisms sharing the same taxonomic rank (family genus species infraspecific variety).
taxonomy
Classification usually in a biological sense.
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

There are currently no active references in this article.

Credits

Dan Crowley (2020)

Recommended citation
Crowley, D. (2020), 'Acer campbellii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-campbellii/). Accessed 2020-10-28.

A deciduous tree usually to 15 m, though up to 30 m. Bark green when young, turning grey to brown with age, smooth. Branchlets glabrous, purplish-red or greenish, bloomed or not, turning darker. Buds ovoid, with 4 pairs of scales. Leaves broadly pentagonal in outline, base cordate to cuneate, (5–)7(–9) lobed, 8–15 × 9–22 cm, lobes ovate, apically acute or acuminate, margins serrulate with acuminate teeth, upper surface somewhat glossy, mid-green, lower surface paler, glabrous except for tufts in vein axils; petiole 4–5 cm long, red to green, glabrous; autumn colours yellow to purple. Inflorescence terminal, paniculate, many flowered. Flowers 5-merous, usually dioecious, pedicels long and slender, stamens eight, inserted inside of the pubescent nectar disc, ovary pilose. Samaras 2.3–2.8 cm long, wings spreading nearly horizontally. Nutlets ovoid. Flowering in May, with unfolding leaves, fruiting in September–October. (Clarke 1988Xu et al. 2008). 

Distribution  BhutanMyanmarChina Southern Sichuan, southern Xizang, northwestern Yunnan India Northern regions NepalVietnam

Habitat Mixed forests between 1800 and 3700 m asl.

USDA Hardiness Zone 7-8

RHS Hardiness Rating H4

Conservation status Least concern (LC)

Taxonomic note The taxonomy of Acer campbellii and its relatives in van Gelderen et al.’s (1994) Series Sinensia has been much confused and a systematic study is required to satisfactorily resolve the group. While van Gelderen et al. (1994) treated A. campbellii as a broad species comprising five subspecies, the Flora of China account (Xu et al. 2008) treated these as distinct species (reducing subsp. chekiangense to a synonym of Acer pubinerve). The treatment of Xu et al. (2008) is broadly followed here, save for the inclusion of A. flabellatum var. yunnanense, which those authors treat as a synonym of A. flabellatum. Xu et al. (2008) placed in synonymy several of the species included recognized by van Gelderen et al. (1994) and these are listed in synonymy under the relevant species here. Further information on the taxonomic debate around each of the accepted taxa is included in the various accounts. A tentative key to the identification of the Series Sinensia taxa as treated here is provided below. Of these, five are not currently known in cultivation. These are: A. chingii, A. kuomeii, A. kweilinense, A. miaoshanicum and A. pseudowilsonii, a new species described from Thailand in 2010 (Chen 2010). A. linganense, treated as part of Series Sinensia by van Gelderen et al. (1994) is considered closer to A. ceriferum by Xu et al. (2008), rather than to members of Series Sinensia (sensu van Gelderen et al. (1994)) Both of these taxa were treated as synonymous with A. duplicatoserratum by Chang & Woo (2011). Acer confertifolium, another included in Series Sinensia by van Gelderen et al. (1994) and treated as a species by Xu et al. (2008) has since been confined to the synonymy of A. tutcheri. Both A. linganense and A. confertifolium are thus omitted from the key. It should also be noted that the four Chinese species in this group that are absent from cultivation (A. chingii, A. kuomeii, A. kweilinense, A. miaoshanicum) have differences described by Eom et al. (2011) as ‘trivial’ and ‘neither correlated with other characters nor always constant within a collection’. Further study on this group is clearly required. Within Acer campbellii Xu et al. (2008) treat var. serratifolium along with the typical var. campbellii. Var. serratifolium has pubescent veins and a cordate base and an elongated inflorescence. In the typical variety, the leaf base is usually truncate and the inflorescence dense. However, such distinctions have not been made in cultivated material.

Acer campbellii is a broad ranging species, occurring in the eastern part of the Himalayan chain into southwest China, and also in the Central Highlands of Vietnam (though absent in the north of that country). It was first discovered by a collector working for William Griffith in Darjeeling, and first introduced by Sir Joseph Hooker from his Himalayan expeditions (1847–1851), who ‘named it in 1875 for his friend, the Superintendent of the hill station at Darjeeling’ (O’Brien 2018). It has been introduced numerous time since. It appears to be more a warm-temperate species than a truely temperate one, and has thus been considered quite tender in gardens. While of course this is quite true for material from parts of its range, particularly so lower elevations, it has proved hardier when introduced from more suitable provenances, such as at altitude in Bhutan, though in many areas it is still prone to damage by late spring frosts (D. Justice, T. Christian, pers. comms. 2020).

It has elegant foliage with serrulate margins, which help distinguish it from typical forms of the related A. flabellatum. The presence of flowers is always a helpful aid to identification (the floral disk and ovary are pubescent in A. campbellii and glabrous in A. flabellatum), and generally required to separate it from A. flabellatum var. yunnanense, which has similar leaf margins, glabrous disks and, sometimes, slightly pubescent ovaries. Seamus O’Brien paints a vivid picture of encountering A. campbellii during multiple visits to Sikkim, including on Mount Maenam where Hooker would have seen it, and where it ‘formed superb column shaped specimens to 27 m’ in the company of Magnolia campbellii, Rhododendron grande, Acer sikkimense, and Schefflera rhododendrifolia (O’Brien 2011).

Like A. flabellatum, A. campbellii is not so commonly encountered in collections as some other members of section Palmata. DJHC 0518 grows at the Hoyt Arboretum, Oregon, while examples of KR 1688, from Bhutan, grow at the David C. Lam Asian Garden, Vancouver (American Public Gardens Association 2017). Numerous specimens grow at Tregrehan in Cornwall, clearly happy in their Cornish climate, though it can do well further north in the United Kingdom if properly sited. Two young trees grow on the Bhutanese hillside at Benmore Botanic Garden in Argyll, grown on from NPSW 387 collected at c. 2950 m asl in Bhutan. However, attempting to grow it even from the hardiest of provenances at the Rogow Arboretum, Poland, would be ‘a waste of time’ (P. Banaszczak, pers. comm. 2020). Many more gatherings made in recent years bear the name A. campbellii, but it seems prudent to err on the side of caution and only cite those that have been seen and confirmed.

Another, as yet unsatisfactorily characterised taxon, relating to A. campbellii, has been introduced to cultivation on several occasions from the Hoang Lien Mountains of northern Vietnam, including collections of BSWJ 11695, BSWJ 11713, FMWJ 13369 and FMWJ 13374 (Crowley 2018). This has been circulated as A. heptaphlebium, which was treated as a synonym of A. flabellatum (as A. campbellii subsp. flabellatum) by van Gelderen et al. (1994), though it is quite distinct, with broad, shallow, ovate lobes and very large samaras. Its flowers also have petals shorter than the sepals, which in A. flabellatum are as long as one another. Furthermore, within Vietnam, A. heptaphlebium grows far further south than the Hoang Lien Mountains, from where this material has been collected. This interesting, new material, bears resemblance both to A. campbellii and A. flabellatum and is clearly a member of this group. Its predominantly seven-lobed leaves have serrated margins, while its flowers have glabrous disks and pubescent ovaries, similar to those of A. sinense. It has been most collected in its ‘red-leaved’ form, with the leaf undersides vividly, and persistently red, though all green examples are also present in its habitat, though evidently not as attractive to the collector. Like much material collected in northern Vietnam in recent years, it is becoming established in collections in parts of our area, though the extent of its hardiness is yet to be fully established. It is also important to note that this taxon is not A. campbellii var. fantsipanense, which, despite its name, is quite unrelated and plants collected as this invariably belong to a relative of A. pectinatum in section Macrantha. See the account of that species for further details.

Identification Key

1a.

Mature foliage untoothed or remotely serrate or if serrate, only towards lobe apices

2

1b.

Mature foliage with serrate to serrulate margins (>10 teeth per side)

8

2a.

Mature petioles and branchlets pubescent

Acer fenzelianum

2b.

Mature petioles glabrous or pubescent, branchlets glabrous

3

3a.

Mature petioles pubescent

Acer chingii

3b.

Mature petioles glabrous

4

4a.

Mature leaves five-lobed, often glaucous beneath, branchlets and petioles stout

Acer sinense

4b.

Mature leaves three to five-lobed, green beneath, otherwise different from above

5

5a.

Mature leaves membranous to chartaceous, three to five lobed, basal lobes often present, though weakly so, margins occasionally serrate in upper parts

Acer wilsonii

5b.

Mature leaves subcoriaceous to coriaceous, three lobed, margins untoothed or occasionally dentate

6

6a.

Samaras less than 4 cm long

Acer tonkinense

6b.

Samaras at least 4 cm long

7

7a.

Inflorescence short, corymbose

Acer calcaratum

7b.

Inflorescence long, paniculate

Acer pseudowilsonii

8a

Leaves usually three-lobed, flowers 4-merous

Acer tutcheri

8b.

Leaves usually three to five or more-lobed, flowers 5-merous

9

9a.

Leaves three to five-lobed, or five-lobed, additional basal lobes sometimes present

10

9b.

More than 5-lobed leaves always present (basal lobes sometimes small)

15

10a.

Ovary pubescent

11

10b.

Ovary glabrous

14

11a.

Petiole glabrous

Acer elegantulum

11b.

Petiole pubescent

12

12a.

Leaf margins serrulate

Acer miaoshanicum

12b.

Leaf margins serrate

13

13a.

Petals shorter than sepals, leaves 10–12 × 11–14 cm

Acer pubinerve

13b.

Petals the same length as sepals, leaves 5–8 × 7–11 cm

Acer kweilinense

14a.

Leaves with pubescent tufts in axils beneath, margin serrulate

Acer oliverianum

14b.

Leaves glabrous beneath, margins crenate to serrate

Acer serrulatum

15a.

Leaf margins sparsely crenate

Acer kuomeii

15b.

Leaf margins serrate to serrulate

16

16a.

Leaf margins serrate, sometimes jaggedly so

17

16b.

Leaf margins serrulate to setose serrulate

18

17a.

Floral disk glabrous, ovary glabrous

Acer flabellatum

17b.

Floral disk glabrous, ovary pubescent

Acer sp. nov.

18a.

Leaf margins serrulate, floral disk and ovary densely pubescent

Acer campbellii

18b.

Leaf margins serrulate to setose serrulate, floral disk glabrous, ovary sometimes slightly pubescent

Acer flabellatum var. yunnanense


'Boney Fingers'

RHS Hardiness Rating: H4

A dwarf form, Acer campbellii ‘Boney Fingers’ turns yellow in autumn (Buchholz & Buchholz Nursery 2019). Whether it belongs to this taxon or to A. flabellatum requires confirmation.


'Exuberance'

RHS Hardiness Rating: H4

Acer campbellii ‘Exuberance’ was discovered and introduced by the Buchholz Nursery in Oregon. Its new growth is purplish-red and it turns a strong orange in autumn (Junker’s Nursery 2017; Buchholz & Buchholz Nursery 2019). Like ‘Boney Fingers’, whether it belongs to this taxon or to A. flabellatum requires confirmation.

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