Coastal Tree Broom

Botanical name: Carmichaelia muritai
Synonyms: Chordospartium muritai
Common name(s): Coastal tree broom

About:
A rare and highly distinctive native broom that forms a small leafless tree with a compact crown of grooved branchlets. It is one of New Zealand’s rarest broom species, naturally restricted to a tiny area of the Marlborough coast. Clusters of small white flowers marked with purple are produced on conspicuous upright flower spikes, followed by small seed pods containing one or two seeds.

Natural habitat:
Deeply eroded coastal cliffs, colluvial fans and free-draining gravel and loess soils near the coast.

Growing environment:
Thrives in fertile, free-draining soils in full sun. Tolerates coastal exposure, drought and wind once established but dislikes humidity, root disturbance and poorly drained conditions.

Endemic distribution:
Endemic to New Zealand. Restricted to the Clifford Bay area of Marlborough in the eastern South Island.

Height:
5–6 m

Width:
2–4 m

Flowering:
December – January

Fruiting:
Present throughout the year

Uses:

• Specimen tree
• Coastal restoration planting
• Dryland revegetation
• Rare plant conservation
• Native wildlife habitat
• Shelter planting in dry regions
• Botanical collections

Appearance:

Growth habit:
Small tree with a stout trunk and dense canopy of compact branchlets. Upper branches are upright while lower branches often droop gracefully.

Leaves:
Leaves are present only on young shoots and are quickly shed. Mature plants appear almost completely leafless.

Stems:
Grey-brown to yellow-green branchlets that are deeply grooved and densely hairy when young, becoming smoother with age.

Flowers:
Small white pea flowers with striking purple-violet markings and veins, produced in dense upright racemes along the branches.

Fruit:
Small greyish-white hairy pods, usually containing a single yellow-green seed, occasionally two.

Ecology:
A specialised coastal species adapted to harsh cliff environments with free-draining soils and low competition. Its flowers provide a nectar source for native insects, while the shrub contributes to the diversity of Marlborough’s coastal ecosystems.

Associated habitats:
Coastal cliffs, gravel fans, loess slopes, dry coastal scrub and erosion-prone coastal bluffs.

How to grow:
Plant in full sun in a sheltered but well-ventilated position with excellent drainage. Once established it is drought tolerant but benefits from fertile soil. Avoid disturbing the roots, as established plants resent transplanting.

Propagation:
Easily grown from fresh seed. Germination is improved by lightly sanding or nicking the hard seed coat before sowing. Hardwood cuttings can be taken but are often difficult to strike.

Cultural use:
Part of New Zealand’s unique native broom flora and an important component of the specialised coastal ecosystems of Marlborough.

Garden value:
A highly unusual and attractive small tree valued for its rarity, architectural branch structure and elegant flowering displays. An excellent choice for collectors of rare New Zealand natives and for dry coastal gardens with excellent drainage.