Meryta sinclairii aka Puka

Meryta sinclairii is a fast-growing evergreen tree that typically reaches 4-8 metres in height with an equal spread, forming a distinctive rounded crown. The leaves are the largest entire leaves in New Zealand's flora, reaching up to 50cm long and 20cm wide, creating a bold tropical appearance. Young plants grow straight up, then branch after flowering to develop the characteristic mushroom-shaped canopy. In containers or coastal conditions, growth may be more compact.

Meryta sinclairii is endemic to New Zealand, occurring naturally only on the Three Kings Islands and Hen and Chickens Islands off the northern coast. It is the sole New Zealand representative of the Meryta genus, which contains about 27 species found across the subtropical and tropical Pacific. The species was first brought to European attention when William Colenso found a sacred tree cultivated by Māori at Whangururu Bay, who had brought it from the Poor Knights Islands.

Meryta sinclairii is highly adaptable to different soil types including chalk, clay, loam, and sand. It prefers humus-rich, free-draining soil and tolerates acidic, neutral, or alkaline pH. Good drainage is essential to prevent phytophthora root rot. In its natural habitat it grows in thick soils in sheltered valleys, but can also tolerate shallow, stony soils on cliffs, indicating some flexibility in soil requirements.

Meryta sinclairii is frost-tender, with leaves suffering damage when temperatures drop below -2°C. It is suitable for USDA zones 9-11 and RHS hardiness zone H2 (requires frost-free conditions). While young plants are particularly vulnerable to frost, mature specimens have proven hardy to approximately -3.8°C (25°F) for short durations in protected situations. The plant has been grown as far south as Dunedin, New Zealand, with winter protection.

Meryta sinclairii naturally grows in relatively sheltered, moist conditions in its island habitat, suggesting a preference for moderate to high humidity. When grown indoors, maintaining adequate humidity helps the large leaves thrive. Consider using a humidifier, placing the pot on a pebble tray with water, or grouping with other plants. Avoid placing near heating vents that create dry air. Outdoor plants in coastal areas benefit from natural salt-spray tolerance.

Meryta sinclairii benefits from feeding during the growing season with a balanced, slow-release fertilizer in spring. Container-grown plants may need more regular feeding than those in the ground. Avoid over-fertilizing, which can promote soft growth susceptible to frost damage.

Meryta sinclairii produces large panicles of small, inconspicuous pale whitish-green flowers from August to April (Southern Hemisphere). The flowers are not particularly showy but are followed by decorative small green berries that ripen to shiny black and persist year-round. Female plants produce fruit, though occasional bisexual flowers occur. The black fruits attract birds and provide ornamental interest, taking about a year to fully mature.

Meryta sinclairii can grow outdoors in frost-free climates, specifically USDA zones 9-11. It thrives in coastal areas, demonstrating excellent tolerance of wind, salt spray, and exposed conditions unusual for a large-leaved plant. Plant in full sun to partial shade with well-drained soil. In marginal climates, choose a sheltered south or west-facing position and protect young plants from frost. Once established, it becomes more resilient and can tolerate brief cold snaps.

Meryta sinclairii generally requires minimal pruning. To encourage branching and a bushier form, remove the growing tips in spring when sap is rising actively. The tree naturally forms a rounded crown after flowering, so shaping is usually unnecessary. Container plants can be trimmed to contain their size. Remove any damaged or dead wood as needed. When pruning, be aware the plant is resinous and heals wounds by forming distinctive callosities.

Container-grown Meryta sinclairii should be repotted when roots begin to circle the pot or emerge from drainage holes. Use a well-draining potting mix with added organic matter. The species performs well in large containers but requires vigilance against root-binding. Repot in spring before active growth begins, moving to a pot only slightly larger than the previous one to prevent overwatering issues. Ensure the new container has adequate drainage holes.

Seed is the primary propagation method for Meryta sinclairii. The plant may self-seed in suitable locations. Cuttings can be attempted but have limited success rates. Take cuttings from healthy, mature growth and place in a well-draining rooting medium. Spring is the optimal time for both seed sowing and cutting propagation.

Meryta sinclairii is generally pest-free, though young plants may suffer rodent damage. The main concerns are fungal diseases: phytophthora (root rot) in overly wet soil, verticillium wilt, and black spot in humid conditions. Once established, these diseases are difficult to treat, so prevention through good drainage is essential. Systemic fungicides can help manage black spot. In the wild, soil-borne pathogens pose a conservation threat to island populations.

The large, glossy leaves of Meryta sinclairii benefit from regular cleaning to maintain their appearance and support photosynthesis. Wipe leaves gently with a damp cloth to remove dust, or give the plant a gentle shower. For indoor plants, monthly cleaning keeps the foliage looking its best. The naturally leathery, glossy surface makes cleaning straightforward. Avoid using leaf shine products which can clog leaf pores.

The main cultivated variety is Meryta sinclairii 'Moonlight', a striking variegated form with leaves displaying cream, yellow, and green coloration. This cultivar has received horticultural awards but is expensive and somewhat disease-prone. 'Moonlight' requires partial shade as the variegated portions can burn in full sun, appearing discoloured. The species form remains more widely available and is generally easier to grow than the variegated cultivar.

Winter protection is the key seasonal consideration for Meryta sinclairii. In frost-prone areas, move container plants indoors or to a frost-free greenhouse before temperatures drop. Young plants are particularly vulnerable and may need fleece protection. Reduce watering in winter when growth slows. Spring is the best time for pruning, repotting, and propagation when sap rises actively. Summer and autumn require regular watering in dry periods, especially for container plants.