Synoum spp.

scentless rosewood

SunPart Shade – Full Shade

HardinessZones 10–11

Overview

Synoum spp. is a small genus in the mahogany family (Meliaceae) from the rainforests of eastern Australia, represented mainly by S. glandulosum, the scentless rosewood. Plants are evergreen shrubs to small trees, typically 10-33 feet (3-10 m) tall, with a slender trunk and a rounded crown. The leaves are pinnately compound with glossy, dark green leaflets dotted with tiny glands. Clusters of small flowers, white to pink and faintly scented, appear among the leaves and are followed by rounded three-valved capsules about 0.4-0.8 inch (1-2 cm) across. The capsules split to reveal seeds wrapped in a bright orange-red aril that draws fruit-eating birds. Synoum spp. grows in the understorey and margins of warm-temperate and subtropical rainforest, often on richer volcanic and alluvial soils. It tolerates shade and regenerates from seed in moist, sheltered gullies. The main limit in cultivation is cold, as plants are frost-tender and need a humid, mild climate with steady moisture; they are slow to establish on dry or exposed sites.

Native Range

Synoum spp. is endemic to eastern Australia, occurring in rainforest from south-eastern Queensland through coastal New South Wales, with isolated populations reaching eastern Victoria.

Suggested Uses

Grown as an understorey or screening shrub and small shade tree in subtropical and warm-temperate gardens, and used in rainforest revegetation. The arillate fruit makes it a food source in plantings aimed at attracting native birds.

How to Identify

Recognised by pinnate leaves whose glossy leaflets are gland-dotted and often slightly notched at the tip, set on a reddish leaf stalk. Small white to pink flowers in branched clusters and rounded capsules that open to show seeds in an orange-red aril are diagnostic. The gland-dotted foliage separates Synoum spp. from the related Toona spp. and Melia spp..

Appearance

Size & Dimensions

Height10' - 33'

Width/Spread8' - 20'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Fall Winter

Flowering is mainly in autumn and winter (March-July in Australia), with small white to pink flowers borne in loose clusters. Capsules ripen over the following months and split open to expose the arillate seeds, which persist briefly before birds remove them.

Detailed Descriptions

Flower Description

white to pink

Foliage Description

dark green

Growing Conditions

Sun Requirements

SunPartial Shade SunFull Shade

Requires 2-6 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)

357912

Soil Types

loam

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

10-15 years

Care & Maintenance

Care Guide

Synoum spp. grows in part shade to full shade on moist, humus-rich, well-drained soils with a pH of about 5.5 to 7.0, matching its rainforest origins. Plants need protection from frost and drying wind and are damaged below about 28°F (-2°C). Steady moisture and a mulched root zone support establishment, though waterlogged ground causes root rot. Growth is slow to moderate, and young plants benefit from overhead shade. Propagation is from fresh seed, which germinates readily, or from cuttings. The narrow climate range is the main constraint outside subtropical and warm-temperate regions.

Pruning

Little pruning is needed. Plants can be shaped when young to form a single trunk or a multi-stemmed shrub, and dead or crossing branches are removed as they appear. Light tip pruning after fruiting keeps growth dense.

⚠️ Toxicity Warning

Unknown