Calicotome villosa aka Hairy Thorny Broom
Taxonomy ID: 3699
Calicotome villosa, commonly known as Hairy Thorny Broom or Spiny Broom, is a deciduous shrub belonging to the Fabaceae (legume) family. Native to the Mediterranean region, this much-branched, spiny shrub typically reaches heights of 1.5 to 3 meters. The species name 'villosa' derives from the Latin 'villus' meaning hair, referring to the plant's distinctive downy, villous (hairy) covering on its twigs, pods, and other parts.
The plant features striate (striped) twigs with sharp terminal spines. Its leaves are digitate with three small leaflets, arranged in clusters along the branchlets. During spring, typically from January through July depending on location, Calicotome villosa produces an abundance of bright yellow papilionaceous (butterfly-shaped) flowers characteristic of the legume family. The flowers are 10-12mm in size with an ample standard petal. Following pollination by insects, the plant develops densely villous (hairy) seed pods. The genus name 'Calicotome' comes from the Greek 'kalux' (calyx) and 'tomos' (cut), referring to the distinctive way the calyx breaks off in a circle after flowering, appearing as if it has been cut.
Calicotome villosa is a characteristic species of Mediterranean garrigue and maquis shrubland, typically found in dry, stony habitats in evergreen scrub near the coast, particularly in areas following woodland clearance. It grows from sea level up to 1200 meters altitude. The plant is well-adapted to hot, dry summers and mild, moist winters. As a nitrogen-fixing legume through symbiotic relationships with soil bacteria, it plays an important ecological role as a pioneer species, quickly colonizing deforested areas and helping to improve soil fertility, creating conditions suitable for native woodland regeneration.
Historically, the thorny branches have been used for low hedging and fencing. The 10th-century Arab physician Muhammad ibn Sa'id al-Tamimi documented using spiny broom in ancient Palestine to flavor sesame oil due to the plant's vanilla-like fragrance, a practice that continues in some regions today.
Common names
Hairy Thorny Broom, Spiny BroomMore information about Hairy Thorny Broom
How difficult is Calicotome villosa to grow?
Calicotome villosa has moderate care requirements suited to experienced gardeners in appropriate climates. The plant demands full sun and cannot tolerate any shade. Excellent drainage is essential, as it can only survive brief cold spells down to -10°C when drainage is perfect. It dislikes root disturbance, so plants should be positioned permanently when young. Once established in a suitable Mediterranean-type climate, it becomes quite low-maintenance due to its drought tolerance.
How often should I water Calicotome villosa?
Calicotome villosa is highly drought-tolerant once established, reflecting its native Mediterranean habitat with hot, dry summers. The plant tolerates both dry and moist conditions but prefers well-drained soil that doesn't stay waterlogged. During establishment, water young plants regularly until root systems develop. Mature plants typically require minimal supplemental watering and can survive extended dry periods.
What type of soil does Calicotome villosa need?
Calicotome villosa adapts to various soil types including light (sandy), medium (loamy), and heavy (clay) soils. The critical requirement is excellent drainage—the plant cannot tolerate waterlogged conditions. It accepts mildly acidic, neutral, or mildly alkaline pH levels. As a nitrogen-fixing legume, it can actually improve poor soils through its symbiotic relationship with soil bacteria.
What are the light requirements for Calicotome villosa?
Calicotome villosa requires full sun and cannot grow in shade. This reflects its native habitat in open Mediterranean scrubland and coastal areas exposed to direct sunlight. Insufficient light will result in poor growth, sparse flowering, and an unhealthy plant.
Is Calicotome villosa toxic to humans or pets?
PFAF reports no known hazards for Calicotome villosa. However, phytochemical research has identified alkaloids (including isoquinoline and tetrahydroisoquinoline types) throughout all parts of the plant, with higher concentrations in seeds and pods. While no toxicity cases are documented, caution is advisable given the alkaloid content. Keep pets and children from ingesting any plant parts until more definitive safety data is available.
How do you propagate Calicotome villosa?
Calicotome villosa can be propagated from seeds or cuttings. For seeds, pre-soak in warm water for 12-24 hours until swollen, then sow in a greenhouse in early spring. For cuttings, take half-ripe wood in July-August and root in a frame, potting each cutting individually. The plant dislikes root disturbance, so establish permanent positions early.
How big does Calicotome villosa grow?
Calicotome villosa is a deciduous shrub that typically reaches 1.5 to 3 meters (5-10 feet) in height at maturity. It develops a much-branched, spreading habit with spiny terminal shoots. Growth rate is moderate. The plant is wider than it is tall, with thorny branches that make it suitable for barrier hedging. As a pioneer species in its native habitat, it establishes relatively quickly when conditions are favorable.
Can Calicotome villosa grow outdoors in my climate?
Calicotome villosa is hardy in USDA zones 7-10 and UK hardiness zone 8. It thrives in Mediterranean-type climates with hot, dry summers and mild, wet winters. The plant can tolerate brief cold periods down to -5 to -10°C but only with perfect drainage—wet cold conditions are fatal. It succeeds in coastal areas and southern regions of temperate zones but is not suitable for cold continental climates or areas with wet, heavy soils.
Where is Calicotome villosa native to?
Calicotome villosa is native to the Mediterranean basin. Its natural distribution spans Southern Europe (Portugal, Spain, France including Corsica, Italy, Sardinia, Sicily, Albania, Greece including Crete, and Turkey), North Africa (Morocco, Algeria, Tunisia, Libya), and Western Asia (Cyprus, Lebanon, Syria, Israel, Jordan, Palestine). It grows in dry, stony habitats in evergreen scrub near the coast, particularly in garrigue and maquis vegetation, from sea level to 1200 meters altitude.
When and how does Calicotome villosa flower?
Calicotome villosa produces abundant bright yellow papilionaceous (butterfly-shaped) flowers typical of the legume family. Flowers are 10-12mm in size and appear in clusters along the branchlets. Bloom time varies by location: January through April in warm Mediterranean areas, extending to May through July in cooler temperate regions. The hermaphrodite flowers are pollinated by insects and followed by distinctive densely hairy (villous) seed pods.
How is Calicotome villosa pollinated?
Calicotome villosa is pollinated by insects. The bright yellow, papilionaceous flowers are hermaphrodite (containing both male and female parts) and attract various pollinating insects, particularly bees. The butterfly-shaped flower structure is characteristic of the Fabaceae family and facilitates insect pollination by providing a landing platform and guiding pollinators to the nectar and pollen.
Does Calicotome villosa need pruning?
Calicotome villosa generally requires minimal pruning. As a naturally branching, somewhat unruly shrub, it can be lightly shaped after flowering if desired. When used as hedging, more regular trimming helps maintain a dense barrier. Take care when pruning as the plant has sharp terminal spines. The plant resprouts well from cuts, similar to other broom species, so it can be rejuvenated through harder pruning if it becomes overgrown.
What temperatures can Calicotome villosa tolerate?
Calicotome villosa tolerates brief cold periods down to -5 to -10°C (14-23°F) but only when grown with perfect drainage. Wet, cold conditions are typically fatal. The plant thrives in hot Mediterranean summers and can handle extreme heat and drought. It is not suited to regions with prolonged freezing temperatures or cold, wet winters. In borderline climates, plant against a south-facing wall for extra warmth and protection.
What are the other uses of Calicotome villosa?
Calicotome villosa has several practical applications beyond ornamental use. Its thorny branches make effective low barrier hedging. As a nitrogen-fixing legume, it improves soil fertility through symbiotic bacteria, making it valuable for land reclamation and as a pioneer species in reforestation projects. Historically, the 10th-century Arab physician al-Tamimi documented using its vanilla-like fragrance to flavor sesame oil in ancient Palestine, a practice still continued in some regions.
Does Calicotome villosa have medicinal uses?
Calicotome villosa has documented traditional and modern medicinal applications. Flowers and leafy stems have been found to possess antimicrobial, antioxidant, antitumor, and cytotoxic properties. Traditional uses included treating furuncles (boils), cutaneous abscesses, and chilblains. The plant contains essential oils, flavones, isoflavones, alkaloids, and triterpenes. However, self-medication is not recommended due to the presence of alkaloids throughout the plant.
Does Calicotome villosa have a fragrance?
Calicotome villosa has a notable vanilla-like fragrance. This distinctive scent was historically prized—the 10th-century Arab physician Muhammad ibn Sa'id al-Tamimi wrote about using spiny broom in ancient Palestine to flavor sesame oil. This traditional use continues in some Mediterranean regions today, where the plant's aromatic qualities are still appreciated for culinary and aromatic purposes.
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