Scientific name: Zanthoxylum flavum

POWO Status: Tree

IUCN Red List threat level: Vulnerable

GPS Location: 17° 42′ 56.76″ N, 64° 49′ 43.01″ W

Observations:

Phenological Markers – West Indian Satinwood (Zanthoxylum flavum)

1. Leaf Behavior
This species is deciduous to semi-deciduous, often shedding leaves during the late dry season, typically January through March in St. Croix.

• Leaves are pinnately compound, with several oval leaflets, sometimes edged with tiny teeth.
• The foliage is lightly aromatic when crushed and often emerges soon after the dry season ends.

Observation Tips:

• Track degree of leaf drop, which may vary by microclimate.
• New leaf flushes emerge bright green and delicate, often in tandem with flowering.

2. Flowering
Flowers are small, pale yellow to greenish, and produced in loose terminal panicles.

• Flowering usually occurs in late dry to early wet season (March–May).
• As a dioecious species, individual trees produce either male or female flowers.
• Flowers are insect-pollinated, especially by small native bees and flies.

Observation Tips:

• Watch for bud development and flower clusters forming at branch tips.
• Document pollinator activity and compare bloom duration across individual trees.

3. Fruiting
Fruits are small, woody capsules that turn from green to dark brown or black when ripe.

• The capsules split open to reveal 1–2 shiny black seeds.
• Fruiting generally occurs June through August, with seeds dispersed by gravity or possibly birds.

Observation Tips:

• Monitor for capsule development, dehiscence, and seed drop.
• Fallen seeds may remain viable under the canopy or be collected for conservation.

4. Growth & Conservation Note

• Z. flavum is considered threatened due to illegal logging and habitat pressure.
• It grows very slowly and thrives in dry, rocky or coastal scrub habitats.
• Phenological data supports seed banking, nursery propagation, and restoration efforts.

5. Seasonal Pattern (St. Croix)

• Jan–Mar: Leaf drop
• Mar–May: Flowering + new leaf flush
• Jun–Aug: Fruiting and seed dispersal
• Sep–Dec: Leaf and branch development; occasional resting phase