Tabernaemontana divaricata: From Botanical History to Care Techniques

Tabernaemontana divaricata, commonly known as Crepe Jasmine or Pinwheel Flower, is an evergreen shrub belonging to the Apocynaceae family. This species is characterized by its grayish-green branches, dark green elliptical or oblong-elliptical leaves, and distinctive white flowers.

I. Botanical History

The genus Tabernaemontana was named after Jakob Theodor von Bergzabern, a 16th-century German botanist and herbalist. The species name “divaricata” refers to the plant’s spreading habit. The common name “Crepe Jasmine” alludes to the flower’s crinkled appearance, reminiscent of crepe paper, while “Pinwheel Flower” describes the flower’s shape when fully open.

II. Morphological Characteristics

Tabernaemontana divaricata typically grows to 1-3 meters in height. The plant is glabrous throughout and contains a milky sap characteristic of the Apocynaceae family.

Leaves: Opposite, elliptical to oblong, 3.5-14 cm long and 1-5 cm wide, with a short acuminate apex and cuneate base. The leaf surface is dark green above and lighter beneath, with 8-10 pairs of lateral veins.

Flowers: Axillary or terminal cymes, usually with paired flowers. The calyx has five oval sepals with ciliate margins. The corolla is white, salverform, with a tube 15-25 mm long and five obliquely obovate lobes, each 13-20 mm long. The distinctive crinkled edges of the corolla lobes give rise to its common names.

Fruit: Paired follicles, linear-lanceolate, 2-7 cm long and 0.6-1 cm in diameter.

Flowering occurs from April to September, with fruiting from July to November.

III. Growing Environment

Crepe Jasmine thrives in warm, humid conditions and is intolerant of cold. It prefers:

• Temperature: Optimal growth above 10°C (50°F). Frost damage can occur below 0°C (32°F).
• Light: Full sun to partial shade. In intense summer heat, partial shade prevents leaf scorch.
• Soil: Adaptable, but prefers fertile, well-drained, slightly acidic soil (pH 5.5-6.5).
• Water: Consistent moisture, but tolerant of short dry periods.
• Humidity: High humidity, benefiting from regular misting in dry conditions.

It naturally occurs in mountainous shrublands at elevations of 1,000-1,600 meters.

IV. Distribution Range

Native to South and Southeast Asia, including:

• China (southern provinces)
• Myanmar
• Thailand
• Nepal
• Bangladesh
• Bhutan
• India

Now widely cultivated throughout tropical and subtropical Asia, and as an ornamental in other warm regions globally.

V. Propagation Methods

1. Stem Cuttings (Primary method):
   • Best done in spring in South China
   • Use 15 cm segments from 1-2 year old branches
   • Remove lower leaves, retain 1-2 upper leaves (trimmed by 2/3)
   • Soak cut ends in water for 2 hours to remove sap
   • Plant in moist sand or potting mix
   • Roots develop in about 25 days, with 85%+ success rate
2. Air Layering:
   • Suitable for larger plants or when cuttings are challenging
3. Seeds:
   • Less common due to slower growth and variable results

VI. Cultivation Techniques

1. Transplanting: Repot every 1-2 years in spring, using fresh, fertile soil mix.
2. Soil: Well-draining, fertile, slightly acidic potting mix. Add organic matter for nutrition.
3. Watering: Keep soil consistently moist but not waterlogged. Increase frequency in summer.
4. Temperature: Maintain above 10°C (50°F). Protect from frost in winter.
5. Light: Bright, indirect light. Morning sun and afternoon shade in hot climates.
6. Fertilizing:
   • May to September: Alternate between balanced liquid fertilizer and organic fertilizer every 7-10 days.
   • Reduce feeding in winter.
7. Pruning:
   • Shape after flowering to maintain form.
   • Remove dead or weak branches in early spring.
8. Winter Care:
   • Move indoors or to protected area if temperatures drop below 5°C (41°F).
   • Reduce watering and fertilizing.

VII. Pest and Disease Control

Common pests include thrips, aphids, and spider mites. Diseases are relatively rare but can include root rot in overly wet conditions.

Pest Management:

1. Regular inspection for early detection.
2. Remove pests manually or with a strong water spray for minor infestations.
3. Use insecticidal soap or neem oil for larger infestations.
4. In severe cases, use appropriate systemic insecticides.

Disease Prevention:

1. Ensure good air circulation.
2. Avoid overwatering.
3. Use sterile potting mix and clean tools.

VIII. Main Varieties

1. Tabernaemontana divaricata ‘Flore Pleno’ – Double-flowered form
2. Tabernaemontana divaricata ‘Variegata’ – Variegated leaves with yellow streaks
3. Tabernaemontana pandacaqui – Related species with single, pinwheel-like flowers

IX. Primary Value

1. Ornamental:
   • Attractive foliage and fragrant flowers
   • Suitable for hedges, borders, container planting, and indoor use in bright areas
2. Medicinal:
   • Contains indole alkaloids with potential therapeutic properties
   • Traditional uses include treating fever, high blood pressure, and inflammation
   • Caution: All parts are toxic if ingested; use only under professional guidance
3. Cultural:
   • Significant in some Asian cultures for religious and ceremonial purposes

X. Conservation Status

Listed as Endangered (EN) on the IUCN Red List due to habitat loss and over-collection for medicinal use. Conservation efforts include:

1. Habitat protection in its native range
2. Ex-situ conservation in botanical gardens
3. Promotion of sustainable cultivation for ornamental and medicinal purposes

In conclusion, Tabernaemontana divaricata is a versatile and valuable plant species with significant ornamental, medicinal, and cultural importance. Its successful cultivation requires attention to its specific environmental needs, particularly regarding temperature, light, and moisture.

As an endangered species, responsible cultivation and conservation efforts are crucial for its long-term survival.