Hoheria sexstylosa Colenso

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Credits

Julian Sutton (2021)

Recommended citation
Sutton, J. (2021), 'Hoheria sexstylosa' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/hoheria/hoheria-sexstylosa/). Accessed 2022-12-04.

Genus

Common Names

  • Lacebark
  • Houhere
  • Long-leaved Lacebark
  • Graceful Lacebark
  • Houhiongaonga

Glossary

acute
Sharply pointed.
branchlet
Small branch or twig usually less than a year old.
divaricate
Widely spreading greatly divergent. Many trees and shrubs from New Zealand have a divaricating form particularly when young whereby the stems become interlaced producing a ‘wire-netting’ effect.
hybrid
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
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.

Credits

Julian Sutton (2021)

Recommended citation
Sutton, J. (2021), 'Hoheria sexstylosa' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/hoheria/hoheria-sexstylosa/). Accessed 2022-12-04.

Small to medium, heteroblastic, evergreen tree to 18 m. Much branched, with rather slender, ascending branches, with sparse stellate hairs on older parts, denser on younger parts and inflorescence; bark dark grey-brown. Branchlets slender, usually dark red-brown, often pendulous towards the tips. Leaves of adult plant: blade lanceolate to ovate-lanceolate, 5–15 × 1–5 cm; base cuneate; apex acuminate, or sometimes obtuse to broadly rounded; margin dentate; upper surface dark- or grey-green, sometimes glossy; lower surface paler and dull; both surfaces ± glabrous, sometimes with sparse glandular hairs especially near the midrib beneath; petiole slender and flexible, 5–10(–20) mm. Juvenile plant a twiggy shrub with subdivaricate branches: leaves rather distant, on very slender petioles ~5 mm long; leaf blade 10–15(–30) × 10–15(–25) mm, broadly ovate to suborbicular in outline, irregularly and deeply 3–5-lobed or incised, base cuneate, margin dentate, both surfaces usually with dense stellate hairs when young. Flowers 18–20(–25) mm across), in 2–5-flowered cymose fascicles or solitary, on 2–3 cm pedicels. Calyx campanulate, ± 6 mm, teeth triangular, usually with dense indumentum; petals white, obliquely oblong, notched, 10–15 mm; styles (5–)6(–7), stigmas capitate; anthers white. Carpels (5–)6–7, compressed, wings broad. (Allan 1961; New Zealand Plant Conservation Network 2021)

Distribution  New Zealand S North Island; widely naturalized in South Island, but probably indigenous in some areas

Habitat Coastal, lowland and montane riparian forest.

USDA Hardiness Zone 8-10

RHS Hardiness Rating H4

Conservation status Not evaluated (NE)

Hoheria sexstylosa is an upright, evergreen, rather hardy species, dark and handsome throughout the year but at its best in summer when covered in small, white flowers. Bean (1981) considered it the commonest evergreen Hoheria species in British gardens. Perhaps this was the case, it may even still be true, but poorly characterized hybrids appear to have blurred the distinction between it and other species, especially H. angustifolia.

Distinguishing H. sexstylosa from other evergreen hoherias is not always easy. H. sexstylosa has a more southerly range than H. populnea, although there is a small region of overlap; it tends to form taller trees, often with distinctly pendulous branchlets, and with somewhat more leathery leaves; its leaf margins usually have finer, more closely spaced teeth; and it most often has 6 rather than 5 carpels, but this is absolutely not diagnostic, despite the name. H. sexstylosa also has a well-differentiated juvenile form with small, lobed leaves on thin twiggy branches, unlike H. populnea, although it does not quite conform to the concept of the divaricate habit (see H. angustifolia). At the southern end of its range, H. sexstylosa overlaps with H. angustifolia, which has a divaricate juvenile form, often seen in mature trees as reverted branches; narrower leaves (to only 1 cm across including teeth) with usually deeper, more spiny teeth; leaves clustered towards branchlet tips; and most often 5 carpels. However, even in the wild, hybridization (especially between H. sexstylosa and H. angustifolia) blurs these distinctions which are already heavily laced with ‘usually’ and ‘typically’ (New Zealand Plant Conservation Network 2021). In gardens these problems are acute (see generic introduction) and it is not easy to find specimens which can confidently be labelled either ‘sexstylosa’ or ‘angustifolia’. Unfortunately this does not stop most gardeners and nurseries doing just that.

First described scientifically in 1885, H. sexstylosa was apparently in British cultivation before 1924 (Edwards & Marshall 2019) and its virtues were quickly recognized. Arnold-Forster (1948) noted its ‘extraordinarily fast’ growth; young potted specimens planted out in his mild but terribly exposed Cornish garden in 1939 were over 7 m tall and flowering profusely by 1945. Of a number of towering specimens at Abbotsbury Subtropical Gardens, Dorset, head gardener Steve Griffith admits that he can no longer tell which were the originals and which seedlings from them, even though the oldest date only from about 1990 (pers. comm. 2021). Significant specimens attributed to this species are mostly found in gardens close to the western and southern coasts of Britain and Ireland (Tree Register 2021), but hoherias of this general type are appearing much more widely in Britain (pers. obs. 2021), and even if they are damaged by the coldest winters, their fast growth makes them a good bet for the short term.

In other parts of our area it is most unusual to find trees labelled H. sexstylosa, but it would probably suit much of the west and north coast of France, milder parts of the Low Countries (it is recorded from Arboretum Wespelaar, Belgium – Plantcol 2021), and in North America the Pacific Northwest.

Apart from the minor cultivar below, several named forms (including ‘Borde Hill’, ‘Snow White’ and ‘Stardust’) are sometimes attributed to H. sexstylosa, but given the genetic mix in gardens, hybrid origins seem every bit as plausible. The names H. ovata Simpson & Thomson and H. “Tararua” refer to ambiguous wild plants variously considered species in their own right, hybrids, or forms of H. sexstylosa (New Zealand Plant Conservation Network 2021; Wagstaff, Molloy & Tate 2010); New Zealand botanists cannot agree, but mercifully these names have not made their presence felt in gardens. The name H. × sexangusta Allan (H. sexstylosa × H. angustifolia) exists (Royal Botanic Gardens, Kew 2021), but is rarely seen in the research or garden literature. Finally, H. populnea var. lanceolata Hook. f. has been variously interpreted as a synonym of H. sexstylosa or as hybrid between H. sexstylosa and H. angustifolia (New Zealand Plant Conservation Network 2021). Edwards & Marshall (2019) note that the RHS First Class Certificate awarded to H. sexstylosa in 1924 was actually given to a plant labelled H. populnea var. lanceolata, raising the possibility that from the beginning, cultivated stocks of H. sexstylosa may not have been ‘pure’. Two British hybrid clones, whose parentage is surmised as H. sexstylosa × angustifolia, have been distributed as H. × lanceolata by Pan-Global Plants, Gloucerstershire (Pan-Global Plants 2020). We can find no evidence that this nothospecific name has ever been validly published, and it is not current in the literature; in any event, this parentage is no more than an informed guess. Both fine plants, it is hoped that they will be given clonal names in the near future, and the name H. × lanceolata abandoned.


'Crataegifolia'

A juvenile form with small, coarsely toothed leaves, which must be repropagated vegetatively at intervals to maintain the juvenile state (Hutchins 2006). Origin unknown.


'Pendula'

The origin of this name, and hence which clone it might properly refer to, is unclear. Plants under this name have been offered since the 1980s or before by a few British growers, notably Burncoose Nurseries, Cornwall.

A notably pendulous tree under this name is grown at Kestellic Garden, Brittany, France (see images). Planted by the house in 1981, it was about 9 m × 25 cm dbh in July 2022 (T. Christian, pers. comm. 2022). Its leaves are narrowly elliptic-ovate.

A roughly 30 year old tree at Abbotsbury Subtropical Gardens has foliage clustered towards the tips of branchlets which, conversely, seem hardly more pendulous than many other forms and hybrids of H. sexstylosa (pers. obs. 2021). Its leaves are ovate, 7–10 × 4(–5) cm, tapering gradually to the acute tips and more abruptly at the base, with large, closely packed, sharp teeth (the Kestellic tree has narrower, more remotely toothed, darker green leaves). The flowers, in clusters of 1–8, open late for this species: it was in very tight bud on 9th August 2021. Photographs of another example with very similar leaves at Caerhays Castle, Cornwall show a similar tree form, although it was noted that another H. sexstylosa nearby has a more upright habit (Williams 2021, 2nd October 2015). Flowering as late as October, it has 5–6 purple styles, petals overlapping in the basal quarter and sepals spreading or slightly reflexed at flowering.

Further research is clearly needed, and as usual hybridity cannot be ruled out in any of these trees.


'Purpurea'

A clone (could it be a hybrid a purple-leaved H. populnea?) with dull purple foliage cultivated in Australia but assumed to have originated in New Zealand. It has had some circulation through the nursery trade in Victoria (D. Teese, pers. comm. 2022). It is possible that the name ‘Purpurea’ is illegitimate if coined after 1959, when Latin cultivar names were outlawed by the horticultural taxonomic code.


var. ovata (G. Simpson & J.S. Thomson) Allan

Synonyms
Hoheria ovata G. Simpson & J.S. Thomson

To 6 m, younger parts with rather dense stellate hairs. Adult leaves ovate-lanceolate to broadly ovate, leathery, 5–8 × 2–4 cm. Flowers 2–3 cm across; carpels usually 5. (Allan 1961New Zealand Plant Conservation Network 2021)

Distribution

  • New Zealand – NW South Island

A taxonomically troublesome plant, in general effect a smaller growing, earlier flowering, hairier version of H. populnea, with smaller, more leathery leaves. It forms stable, true breeding populations in parts of Westland and Nelson where neither H. populnea nor H. sexstylosa grows (New Zealand Plant Conservation Network 2021). Originally described as a species, it has been treated as a variety of H. sexstylosa (Allan 1961), and as a stable hybrid between H. populnea and H. sexstylosa (New Zealand Plant Conservation Network 2021). The molecular data of Wagstaff, Molloy & Tate (2010) are at least compatible with this hybrid origin. The name does not seem to have been attached to plants grown in our area.