1. Introduction

Habitat and Distribution

Licuala orbicularis is endemic to the island of Borneo, specifically found in Sarawak (Malaysia) and West Kalimantan (Indonesia). This remarkable palm inhabits lowland mixed dipterocarp forests from near sea level to 400 meters elevation, with highest populations in alluvial areas along rivers and in periodically flooded forest zones. It thrives in deep shade beneath the forest canopy where light levels are often below 2% of full sunlight. The species shows a strong preference for areas with consistent high humidity and annual rainfall exceeding 3,000mm. Its extremely limited distribution makes it one of the rarest palms in the wild, with most populations occurring in areas increasingly threatened by deforestation.

Native Continent

Taxonomic Classification

Synonyms

• Licuala rotundifolia hort. (misapplied name)
• Sometimes confused with juvenile L. grandis
• Occasionally mislabeled as Licuala sp. "Round Leaf"

Common Names

• Round-leaf licuala (English)
• Circular fan palm (English)
• Palas bulat (Malay - "round palas")
• 圆叶轴榈 (Chinese - "yuán yè zhóu lǘ")
• Palmier parasol (French)

Expansion in the World

L. orbicularis has become increasingly popular in cultivation:

• Common in Southeast Asian botanical gardens
• Singapore Botanic Gardens (multiple specimens)
• Growing popularity in private collections worldwide
• Available from specialist palm nurseries
• Seeds regularly offered internationally
• Tissue culture propagation increasing availability
• IUCN Red List status: Vulnerable (due to habitat loss)

Its spectacular circular leaves make it one of the most sought-after Licuala species.

2. Biology and Physiology

Morphology

Trunk

L. orbicularis is a solitary, slender-trunked palm reaching 2-4 meters in height (rarely to 5m) with a diameter of 3-5cm. The trunk is covered with persistent, fibrous leaf bases in young plants, becoming smooth and ringed with age. The internodes are closely spaced (2-4cm), giving the trunk a bamboo-like appearance. The trunk color ranges from green in youth to gray-brown at maturity.

Leaves

The leaves are the species' most distinctive feature - perfectly circular to slightly oval, undivided (entire), and peltate (stem attached to center of blade). Mature leaves measure 60-100cm in diameter, though cultivated specimens can reach 120cm in optimal conditions. The leaf blade is pleated with 30-40 ribs radiating from the center, creating a parasol-like appearance. Leaves are glossy dark green above and lighter green below with no indumentum. The petiole is 1-2 meters long, slender, with small teeth along the margins becoming smooth with age.

Inflorescence

The interfoliar inflorescence emerges from among the leaves, extending beyond them. It is branched to 2-3 orders, 60-100cm long, with a slender peduncle. The rachillae are thin, bearing small bisexual flowers arranged in clusters. Flowers are cream to pale yellow, fragrant, about 3-4mm across. Flowering can occur throughout the year in cultivation but peaks during warm, humid seasons.

Fruits

Globose to ovoid, 8-12mm diameter, ripening from green through orange to bright red. Each fruit contains a single seed with thin flesh. Fruiting is relatively rare in cultivation outside the tropics.

Life Cycle

L. orbicularis has a moderate life cycle for a small palm:

• Germination to Seedling (0-2 years): Slow initial growth
• Juvenile Phase (2-8 years): Leaf division reduces, becoming entire
• Sub-adult Phase (8-15 years): Trunk development, circular leaves
• Adult Phase (15-60+ years): Full size, regular flowering
• Longevity: Estimated 80-100 years

First flowering typically occurs at 12-20 years or when trunk reaches 1-2 meters.

Specific Adaptations to Climate Conditions

• Deep Shade Tolerance: Thrives in <2% full sunlight
• Circular Leaves: Maximum light capture in understory
• Peltate Attachment: Allows flexible leaf orientation
• Thin Trunk: Minimizes self-shading
• Moisture Indicators: Leaves droop when dry
• Wind Sensitivity: Entire leaves tear easily

3. Reproduction and Propagation

Seed Reproduction

Seed Morphology and Diversity

L. orbicularis produces globose seeds 6-8mm in diameter after removal of the thin pericarp. Seeds have a smooth, tan to brown surface with a small hilum. The endosperm is homogeneous and the embryo lateral. Fresh seed weight ranges from 0.3-0.5 grams. Limited genetic diversity exists due to small, fragmented wild populations.

Detailed Seed Collection and Viability Testing

Viability Testing:

• Float test: Viable seeds sink
• Visual: Plump, heavy seeds best
• Cut test: White, firm endosperm
• Fresh viability: 85-95%
• One month: 60-70%
• Three months: 20-30%
• Six months: <5%

Pre-germination Treatments

Fruit Processing:

• Remove pericarp immediately
• Clean thoroughly
• Never allow drying
• No fermentation needed

Scarification:

• Not typically necessary
• Light filing optional
• Avoid damaging embryo

Soaking:

• 24-48 hours in warm water
• Change water daily
• Add fungicide

Step-by-step Germination Techniques

1. Medium: 50% peat, 30% perlite, 20% vermiculite
2. Container: Individual small pots preferred
3. Planting: Sow 1cm deep
4. Temperature: Constant 28-32°C (82-90°F)
5. Humidity: 85-95% critical
6. Light: Deep shade immediately
7. Moisture: Never allow drying

Germination Difficulty: Moderate to difficult

Germination Time

• First germination: 45-90 days
• Peak germination: 90-150 days
• Complete process: up to 300 days
• Success rate: 60-80% with fresh seeds

Seedling Care and Early Development

Year 1:

• Maintain germination conditions
• First leaves divided
• Growth very slow
• No fertilization

Years 2-3:

• Gradually reduce humidity to 80%
• Begin light feeding
• Leaves becoming less divided
• Maintain deep shade

Years 4-5:

• Nearly circular leaves appearing
• Can reduce shade slightly
• Regular feeding program
• Growth rate increases

Advanced Germination Techniques

Hormonal Treatments for Germination Enhancement

4. Cultivation Requirements

Light Requirements

Species-specific Light Tolerance Ranges

• Seedlings (0-3 years): 50-200 μmol/m²/s (deep shade essential)
• Juveniles (3-8 years): 100-400 μmol/m²/s (heavy shade)
• Sub-adults (8-15 years): 200-600 μmol/m²/s (moderate shade)
• Adults: 300-800 μmol/m²/s maximum (bright shade)

Never tolerates direct sunlight.

Seasonal Light Variations and Management

• Consistent deep shade year-round
• Increase protection in summer
• Morning sun fatal to leaves
• Dappled light ideal

Artificial Lighting for Indoor Cultivation

• Low light requirements advantageous
• Standard fluorescent adequate
• 10-12 hour photoperiod
• 50-150 foot-candles sufficient

Temperature and Humidity Management

Optimal Temperature Ranges

• Ideal: 24-30°C (75-86°F)
• Acceptable: 20-32°C (68-90°F)
• Minimum survival: 15°C (59°F)
• Maximum tolerance: 35°C (95°F)
• Consistent temperatures preferred

Cold Tolerance Thresholds

• Damage threshold: 18°C (64°F)
• Severe damage: 15°C (59°F)
• Fatal temperature: 10°C (50°F)
• No frost tolerance whatsoever

Hardiness Zone Maps

• USDA Zones: 10b-11
• Marginal in Zone 10a
• Sunset Zones: 23-24
• European hardiness: H1a

Humidity Requirements and Modification

Soil and Nutrition

Ideal Soil Composition and pH

Nutrient Requirements Through Growth Stages

Seedlings (0-3 years):

• No fertilization year one
• Very dilute feeding thereafter
• 1/8 strength monthly

Juveniles (3-8 years):

• NPK ratio: 3-1-2
• Monthly during growing season
• Half strength maximum

Adults (8+ years):

• NPK ratio: 10-5-10
• Bi-weekly in summer
• Full strength acceptable

Organic vs. Synthetic Fertilization

Organic Program:

• Fish emulsion ideal
• Worm casting tea
• Composted manure (dilute)
• Slow, steady nutrition

Synthetic Approach:

• Controlled-release preferred
• Liquid feeds supplement
• Micronutrients essential
• Avoid salt buildup

Micronutrient Deficiencies and Corrections

• Iron: Common - chelated iron monthly
• Magnesium: Epsom salts quarterly
• Manganese: Foliar spray if needed
• Calcium: Rarely deficient

Water Management

Irrigation Frequency and Methodology

• Consistent moisture critical
• Never allow drying
• Daily in hot weather
• Reduce slightly in winter

Drought Tolerance Assessment

Water Quality Considerations

• Prefers rainwater or RO
• Sensitive to salts and chlorine
• TDS below 100 ppm ideal
• pH 6.0-6.5 optimal

Drainage Requirements

• Good drainage essential despite moisture needs
• No waterlogging tolerance
• Elevated planting helpful
• Organic mulch beneficial

5. Diseases and Pests

Common Problems in Growing

• Fungal leaf spots: High humidity issue
• Scale insects: Common pest
• Root rot: Poor drainage
• Leaf browning: Low humidity

Identification of Diseases and Pests

Fungal Pathogens:

• Pestalotiopsis: Gray-brown spots
• Cylindrocladium: Leaf blight
• Pythium: Root rot
• Anthracnose: In wet conditions

Common Pests:

• Scale insects: Brown/white bumps
• Mealybugs: White cottony masses
• Spider mites: In dry conditions
• Thrips: Silvery streaks

Environmental and Chemical Protection Methods

Cultural Controls:

• Optimize humidity levels
• Ensure air circulation
• Remove affected leaves
• Quarantine new plants

Chemical Options:

• Neem oil for most pests
• Systemic insecticides if severe
• Fungicides preventatively
• Minimal chemical use preferred

6. Indoor Palm Growing

Specific Care in Housing Conditions

Indoor Advantages:

• Low light needs ideal
• Small size manageable
• Spectacular appearance
• Conversation piece

Success Requirements:

• High humidity essential
• Stable temperatures
• Protection from drafts
• Regular misting

Replanting and Wintering

Replanting Schedule:

• Every 2-3 years
• Spring timing best
• When rootbound only

Replanting Process:

• Water day before
• Gentle handling essential
• Minimal root disturbance
• Same planting depth
• High humidity recovery

Winter Care:

• Maintain minimum 20°C (68°F)
• Increase humidity
• Reduce watering slightly
• No fertilization
• Maximum available light
• Avoid heating vents

7. Landscape and Outdoor Cultivation

Garden Applications

• Understory specimen supreme
• Shaded borders
• Container focal point
• Conservatory centerpiece

Design Impact

• Unique circular leaves
• Tropical elegance
• Small space suitable
• High ornamental value

8. Cold Climate Cultivation Strategies

Cold Hardiness

Minimal - truly tropical species requiring constant warmth.

Winter Protection

• Indoor/greenhouse only
• Cannot survive outdoors in temperate zones
• Heated space essential

Hardiness Zone

• USDA 10b-11 only
• Death below 10°C (50°F)

Winter Protection Systems and Materials

• Controlled environment only
• Heating essential
• Humidity systems required
• No outdoor options in cold climates

Establishment and Maintenance in Landscapes

Planting Techniques for Success

Site Selection (Tropics Only):

• Deep shade mandatory
• High humidity area
• Protected from wind
• Rich soil

Soil Preparation:

• Deeply amended
• Organic matter rich
• Perfect drainage
• Mulch heavily

Planting Process:

• Minimal root disturbance
• Plant at same depth
• Water thoroughly
• Shade cloth if needed

Long-term Maintenance Schedules

Daily:

• Moisture checking
• Misting if needed

Weekly:

• Thorough inspection
• Pest monitoring
• Humidity check

Monthly:

• Fertilization (growing season)
• Remove damaged leaves
• Check soil pH
• Growth documentation

Annually:

• Soil testing
• Mulch renewal
• Support evaluation
• Photo documentation