Bindweed
Convolvulus tricolor
Bindweed (Convolvulus tricolor), commonly known as dwarf morning glory or tricolor bindweed, is a charming annual flowering plant in the family Convolvulaceae. Despite sharing its common name with the notorious invasive bindweeds of the genus Calystegia and Convolvulus arvensis, C. tricolor is a diminutive, well-behaved ornamental prized for its vividly tri-colored flowers.
• Produces funnel-shaped blooms typically displaying three distinct color zones — a bright yellow throat, a white middle band, and a vivid blue, violet, or magenta outer margin
• Each flower opens for only a single day, typically in full sun, and closes by afternoon or on overcast days
• Widely cultivated as a bedding plant, edging plant, and container specimen in temperate gardens worldwide
• The specific epithet "tricolor" directly references the flower's characteristic three-toned coloration
Taxonomie
• Natural range includes countries bordering the Mediterranean Sea such as Spain, Italy, Greece, Turkey, Morocco, and Algeria
• Typically found in coastal regions, dry hillsides, open scrubland, and disturbed ground at low elevations
• Has been introduced and naturalized in other temperate regions as a garden escapee, though it rarely becomes invasive unlike its weedy relatives
• The genus Convolvulus comprises approximately 250 species distributed across temperate and tropical regions worldwide, with the greatest diversity in the Mediterranean and western Asia
Stems:
• Slender, trailing to ascending, often branching from the base
• Covered with fine, soft hairs (pubescent)
• Green, sometimes with a reddish tinge
Leaves:
• Simple, alternate, lanceolate to ovate-lanceolate (~2–5 cm long)
• Entire margins, slightly hairy on both surfaces
• Lower leaves may be spatulate; upper leaves progressively narrower
• Short petioles or nearly sessile on upper stems
Flowers:
• Solitary, borne on long axillary peduncles (~3–8 cm)
• Funnel-shaped (salverform), ~2.5–4 cm in diameter
• Five fused petals forming the characteristic trumpet shape
• Calyx of five sepals, hairy, persistent
• Five stamens and a single pistil with a two-lobed stigma
• Color pattern: golden-yellow throat → white band → blue/violet/magenta limb (the signature "tricolor" pattern)
Fruit & Seeds:
• Capsule, globose, ~5–6 mm diameter, containing 2–4 seeds
• Seeds are small, dark brown to black, roughly triangular, with a rough, granular texture
• Seeds exhibit physical dormancy due to a hard seed coat, enabling long-term viability in soil seed banks
• Prefers full sun; flowers open widest in direct sunlight and close in shade or overcast conditions
• Commonly found on dry, sandy, or rocky soils, roadsides, field margins, and coastal cliffs
• Tolerant of poor, nutrient-deficient soils and moderate drought once established
• Flowers are pollinated primarily by bees and other generalist insect pollinators attracted to the bright coloration and accessible nectar
• As an annual, it completes its entire life cycle — germination, growth, flowering, seed set, and death — within a single growing season
• Seeds germinate in spring when soil temperatures reach approximately 15–20°C
Light:
• Full sun essential for abundant flowering; at least 6 hours of direct sunlight daily
• Flowers will not open properly in shade or on heavily overcast days
Soil:
• Well-drained, sandy or loamy soil preferred
• Tolerates poor, dry, and slightly alkaline soils
• Avoid heavy, waterlogged, or overly rich soils, which promote excessive foliage at the expense of flowers
Watering:
• Moderate watering during establishment; drought-tolerant once rooted
• Avoid overwatering — susceptible to root rot in poorly drained conditions
Temperature:
• Sow after last frost when soil has warmed; optimal germination at 15–20°C
• Thrives in warm conditions; flowering peaks in summer (June–September in the Northern Hemisphere)
• Not frost-hardy; killed by the first hard frost in autumn
Propagation:
• Direct sow outdoors after last danger of frost, or start indoors 4–6 weeks earlier
• Seeds benefit from scarification (lightly nicking the hard seed coat) or soaking in warm water for 12–24 hours before sowing to improve germination rates
• Sow seeds ~3 mm deep; germination typically occurs within 7–21 days
• Self-seeds readily in favorable conditions, returning year after year in mild climates
Common Problems:
• Aphids may colonize young growth
• Powdery mildew in humid, poorly ventilated conditions
• Poor flowering → insufficient sunlight or over-fertilization with nitrogen
Anecdote
The daily rhythm of Convolvulus tricolor's flowers is a beautiful example of a plant's built-in light-sensing clock: • Each flower opens at dawn and closes by mid-afternoon, regardless of whether pollinators have visited — a behavior controlled by circadian rhythms and light intensity • The flowers are essentially "solar-powered" — they track light levels and only unfurl fully when sufficient sunlight is available, conserving energy on cloudy days The Convolvulaceae family includes some of the world's most economically important — and most troublesome — plants: • Sweet potato (Ipomoea batatas) — a staple food crop feeding hundreds of millions of people globally • Convolvulus arvensis (field bindweed) — considered one of the world's worst agricultural weeds, with root systems extending over 6 meters deep • Despite being in the same family, C. tricolor is a well-mannered garden annual that rarely escapes cultivation The genus name Convolvulus comes from the Latin "convolvere," meaning "to twine" or "to entwine," referring to the climbing or trailing growth habit characteristic of many species in the genus. While C. tricolor is more of a low sprawler than a vigorous climber, its larger relatives can twine around neighboring plants and structures with remarkable speed — some species can complete a full rotation around a support in as little as two hours.
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