Table of Contents
Pronunciation:
Introduction
Hibiscus trionum, commonly known in the USA as Flower-of-an-Hour, is a species of hibiscus that is also known by other names such as Venice Mallow and Bladder Hibiscus. The plant is named for its flowers, which typically last for only a short time each day.
Classification
- Kingdom: Plantae
- Phylum: Angiosperms
- Class: Eudicots
- Order: Malvales
- Family: Malvaceae
- Genus: Hibiscus
- Species: H. trionum
Description
Hibiscus trionum is an annual herbaceous plant known for its attractive, but short-lived flowers. It has ornamental value due to its distinctive blooms and is sometimes grown in gardens for this reason. However, in some regions, it is considered an invasive weed that can outcompete native plants and disrupt local ecosystems.
Size
The plant typically grows to about 20-50 cm (8-20 inches) in height, though it can occasionally reach up to 80 cm (31 inches).
Leaves
The leaves of Hibiscus trionum are variable in shape, usually lobed or with toothed margins, and are alternately arranged along the stem.
Flower
The flowers are its most distinctive feature, with pale yellow petals and a dark purple or brown center. They are about 4-6 cm (1.5-2.4 inches) in diameter and bloom in the morning, closing by the afternoon, hence the name Flower-of-an-Hour.
Fruit
The fruit is a capsule with a papery outer layer, often referred to as a “bladder,” which encloses the seeds.
Stem
The stem of Hibiscus trionum is typically slender and branched, with a green to reddish coloration.
Cultivation and Care
Planting
Plant seeds directly into the ground after the last frost, or start them indoors several weeks before the last frost if desired.
Soil Preference
Hibiscus trionum prefers well-drained soil but can tolerate a variety of soil types.
Watering
The plant requires moderate watering, especially during dry periods, but does not tolerate waterlogged conditions.
Sun Requirements
Full sun to partial shade is ideal for the growth of Flower-of-an-Hour.
Pruning
Pruning is not typically necessary for Hibiscus trionum, but if you wish to shape the plant or remove dead flowers, use clean, sharp scissors or pruning shears. Prune in the late afternoon after the flowers have closed.
Propagation
Propagation is usually done by seed, as the plant is an annual and completes its life cycle in one year.
Health & Safety
There is no widespread evidence to suggest that Hibiscus trionum is poisonous or toxic to humans, dogs, or cats. However, as with any plant, it is always best to exercise caution and prevent pets and children from ingesting plants not intended for consumption.
The plant is not known to be thorny, spiky, or to cause contact dermatitis or other skin irritations.
Pests and Problems
Hibiscus trionum can be affected by common pests such as aphids (Aphidoidea) and spider mites (Tetranychidae). These pests typically feed on the sap of the plant, which can lead to weakened growth and sometimes the transmission of plant diseases. Control measures include regular monitoring of the plant, encouraging natural predators, or using appropriate insecticidal treatments if necessary.
Additionally, the plant can suffer from fungal diseases, such as rust and root rot, when conditions are too moist or when there is poor air circulation. To prevent these issues, ensure proper spacing between plants and avoid overwatering.
Caresheet Data
| Plant Name: | hibiscus trionum |
|---|---|
| Etymology: | Hibiscus: From Latin hibiscum, which was derived from Greek ἰβίσκος (hibískos), referring to marshmallow plants. Trionum: From the Greek “treis” meaning three, and “onos” meaning a donkey or ass, possibly referring to the three-parted seed capsules which may have been thought to resemble a donkey’s hoof. |
| Common Name: | Flower-of-an-Hour |
| Genus: | Hibiscus |
| Species: | trionum |
| Family: | Malvaceae |
| Height: | 16-24 in / 1.3-2 ft / 40-60 cm / 0.4-0.6 m |
|---|---|
| Width and Spread: | 12-18 in / 1-1.5 ft / 30-45 cm / 0.3-0.45 m |
| Plant Type: | Annual/perennial flowering plant |
| Habit/Form: | Annual herbaceous plant |
| Leaf Type: | Alternate, simple, ovate to lanceolate, often with a toothed or lobed margin |
| Leaf Arrangement: | Alternate |
| Leaf Shape: | Lanceolate to ovate, often with lobed margins |
| Leaf Margin: | Dentate |
| Leaf Color: | Green |
| Fragrance: | Yes; mild and sweet fragrance |
| Stem Description: | Herbaceous, branching, slightly hairy |
| Stem Is Aromatic: | No |
| Texture: | Papery |
| Leaf Feel: | Soft, slightly hairy |
| Leaf Length: | 5-8 cm |
| Leaf Description: | Alternate, ovate to lanceolate, 3-lobed, toothed margins, 2-8 cm long. |
| Hairs Present: | Yes |
| Light Requirements: | Full sun to partial shade |
|---|---|
| Soil Preference: | Well-drained soil with a neutral to slightly alkaline pH. |
| Water Requirements: | Moderate; keep soil consistently moist but not waterlogged. |
| Fertilizer Requirements: | Balanced, water-soluble fertilizer with an NPK ratio of 10-10-10 or 20-20-20, applied every 4 to 6 weeks during the growing season. |
| Pruning Requirements: | Prune after flowering to maintain shape and encourage bushier growth. |
| Seed Germination Time: | 5-14 days |
| Display/Harvest Time: | Late summer to early autumn |
| Fruit/Seed Production: | Fruit |
| Growth Rate: | Fast-growing |
| Growth Habit: | Annual or short-lived perennial |
| Root System Type: | Fibrous root system |
| Fruit Type: | Capsule |
|---|---|
| Fruit Description: | Capsule, ovoid to globose, loculicidal, containing numerous reniform seeds. |
| Flower Color: | Pale yellow with a dark purple center |
| Flower Shape: | Funnel-shaped |
| Flower Inflorescence: | Solitary, axillary, with a 5-lobed epicalyx. |
| Flowering Season: | Summer to early fall |
| Bloom Duration: | 1 day per flower, but the plant continues to produce flowers over several weeks in summer. |
| Drought Tolerance: | Moderate |
|---|---|
| Frost Tolerance: | Sensitive to frost |
| Heat Tolerance: | Intermediate (can tolerate some heat but not extreme high temperatures) |
| Wind Tolerance: | Moderate |
| Shade Tolerance: | Low to moderate shade tolerance |
| Salt Tolerance: | Moderate |
| Soil Compaction Tolerance: | Low |
| USDA Plant Hardiness Zones: | 10-11 |
| Photoperiod Sensitivity: | Short-day plant |
| Pollinator Attraction: | Yes; bees, butterflies, and other insects. |
|---|---|
| Wildlife Value: | Low; attracts bees and other pollinators. |
| Problematic Insects: | Aphids, whiteflies, spider mites |
| Allelopathic Properties: | Yes |
| Habitat Enhancement: | Hibiscus trionum provides nectar and pollen for pollinators, creates microhabitats for small organisms, and contributes to soil health through leaf litter decomposition. |
| Erosion Control Potential: | Low |
| Landscape Location: | Sunny borders, cottage gardens, annual or mixed beds |
| Landscape Theme: | Cottage garden; tropical garden; mixed borders; pollinator-friendly garden |
| Design Feature: | Yes, as ornamental plant in gardens, for its attractive flowers and foliage. |
| Ethnobotanical Significance: | Used traditionally for skin care and as a mild laxative; seeds considered edible. |
| Naturalization Ability: | Moderate |
| Companion Planting Suitability: | Compatible with vegetables like lettuce; avoid proximity to other hibiscus species to prevent competition. |
| Edibility: | Yes |
|---|---|
| Edible Parts: | Flowers, leaves |
| Toxicity: | No |
| Poison Parts of Plant: | Hibiscus trionum is not known to be poisonous. |
| Toxic to Humans: | No |
| Toxic to Cats: | No |
| Toxic to Dogs: | No |
| Causes Contact Dermatitis: | No known common cause |
| Air Purification Qualities: | No established air purification qualities. |
| Medicinal Properties: | Antioxidant, antimicrobial, anti-inflammatory, analgesic, antipyretic, diuretic |
| Thorniness or Spikiness: | No |
Sources and Additional Reading
- Hibiscus trionum – Plant Finder – Missouri Botanical Garden (www.missouribotanicalgarden.org)
- USDA Plants Database (plants.usda.gov)
- Flower-of-An-Hour (Hibiscus trionum) · iNaturalist (www.inaturalist.org)
- Hibiscus trionum L. – World Flora Online (www.worldfloraonline.org)
- Hibiscus trionum Flower Of An Hour PFAF Plant Database (pfaf.org)
- Hibiscus trionum L. | Plants of the World Online | Kew Science (powo.science.kew.org)
- Hibiscus trionum (Flower of an Hour) – Minnesota Wildflowers (minnesotawildflowers.info)
