Pseudopanax crassifolius, also known as horoeka or lancewood, is a heteroblastic tree belonging to the family Araliaceae. It is endemic to New Zealand and found throughout the country from sea level up to about 750 metres (2,460 feet) in lowland to montane shrublands and forests. The juvenile form, which lasts between 15 and 20 years, is easily recognised. The leaves are stiff and leathery with a prominent central rib, about 1 cm wide and up to 1 m long with irregular teeth, all growing downwards from a central stem. The young trunk has characteristic vertical swollen ridges. As the tree gets older the stem begins to branch, producing a bushy top. The leaves also become wider and shorter, losing their teeth. It is only when the tree is mature that it adopts a typical tree shape. The difference between the juvenile and adult tree's appearance is so drastic that the two forms were initially described as separate species and even genera by early botanists, including the botanists accompanying Captain James Cook during his first voyage to New Zealand. One of the theories about this curious change of appearance is that the young plant had to protect itself against browsing by the moa, a group of giant flightless birds that once roamed New Zealand's bush. Once above moa height, it was out of danger and turns into a "regular" tree. A study of leaf colour development in P. crassifolius found that leaves of seedlings would blend with leaf litter, while juvenile leaf colouration would draw attention to their spines. A closely related Chatham Island species, which evolved in the absence of moa, did not display these changes. Closely related is Pseudopanax ferox, the toothed lancewood. It is similar to P. crassifolius except the leaves are more abundant and severely toothed, resembling remotely a bandsaw blade.
Description
Pseudopanax crassifolius is a heteroblastic plant, meaning that it has different leaf forms and growth habits depending on its growth stage. These growth stages, which are largely related to the plant height, are: seedling, juvenile, transitional, and adult. A juvenile tree is single-stemmed with long and narrow deflexed leaves, typically below the height of 3–5 m (9.8–16.4 ft). As an adult, P. crassifolius can reach a height of 15 m. It appears as a round-headed tree due to being multi-branched, making it look more like a "typical tree" than its previous forms.
Leaves Seedling leaves are smaller and thinner compared to the following growth stages, but they gradually become longer as the plant grows out from the leaf litter, starting from cotyledon. Leaves are initially green but become more mottled brown and leathery as the plant grows. Juvenile leaves, which are produced up to 4 m (13 ft) or before the tree branches, are especially long and narrow (1 m (3 ft 3 in) long by 1–1.5 cm (0.39–0.59 in) wide) – similar in shape to a lance. They are dark green with a sharply toothed margin and prominent yellow or orange midrib. Leaves are also rigid and straight, but angled downwards from the stem, 45–60º from horizontal. Intermediate leaves appear once the tree has branched, typically above the height of 4–5 m. They are an intermediate between juvenile and adult leaves, being shorter and wider than juvenile leaves. Adult leaves are shorter and wider (10–20 cm (3.9–7.9 in) long by 2–3 cm (0.79–1.18 in) wide), with a less prominent midrib and toothed or entire margin. Additionally, leaves are simple, alternate, and grow outwards or upwards from the branch. They typically appear once the tree is above 5 m and branched. Adult leaves also have greater frost resistance than juvenile leaves.
Trunk The trunk of a juvenile tree is slender, straight, unbranched, and ridged down its length. For adult trees, the trunk can be up to 50 cm (20 in) in diameter. It has horizontal lenticels and smooth, grey, or mottled bark. At this life stage, the top of the tree has branched and the juvenile leaves have fallen off, producing a rounded head with a naked stem.
Flowers The tiny, 4 mm (0.16 in) diameter, pale yellow to green flowers are clustered in large terminal umbels, 30 cm (12 in) across. The flowers are bisexual, so they have five stamens and five styles.
Fruits The fleshy fruits, which are usually dark purple to black when ripe, are 3–4 mm (0.12–0.16 in) in diameter and round. They contain five seeds per berry, with the five locules each containing one seed.
Taxonomy The species was first described by Daniel Solander in his unpublished manuscripts detailing the First voyage of James Cook in 1779. Solander The juvenile and adult forms of the plant were so visually different that Solander used two different names for the plant: Aralis crassifolia for the adult form, and Xerophylla longifolia for the juvenile form. The first formal description of the plant was made in 1839 by Allan Cunningham, who retained the name Aralis crassifolia. In 1859, Karl Koch placed the species in the genus Pseudopanax, which remains the modern scientific name used today.
Etymology The species epithet crassifolius means "thick leaved". The Māori language name horoeka likely derived from Proto-Polynesian *Solo[w]eka or *Qoromea, both hypothetical words used to refer to unknown species of tree. Possible cognates include Tahitian oroea, used to describe Cyclophyllum barbatum, Rennellese kogomea, a word for Hibiscus cooperi, and Hawaiian olomea, used to describe Perrottetia sandwicensis. All three lancewood species (P. crassifolius, P. ferox, and P. linearis) are known as horoeka by Māori. The English language name lancewood refers to the Māori cultural use of the juvenile plant as a lance for bird hunting. An alternative early name no longer in use is the "fishbone tree", a reference of the juvenile plant's leaves resembling the spine and ribs of a fish.
Range Pseudopanax crassifolius is endemic to New Zealand. It is abundant and widespread in the North Island, South Island, and Stewart Island.
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