Bur-bearing plants such as Xanthium species are often single-stemmed when growing in dense groups, but branch and spread when growing singly.
Burs catch on the fur of passing animals or the clothing of people. The hooks or teeth can be irritants and very hard to remove from clothing, such as wool or cotton. The bur of burdock was the inspiration for Velcro.
Burs serve the plants that bear them in two main ways. First, they tend to repel some herbivores, much as other spines and prickles do. Second, they are mechanisms of seed dispersal by zoochory (dispersal by animals) and anthropochory (dispersal by humans). Plants with burs rely largely on living agents to disperse their seeds.
Common plants with burs
Common bur-bearing plants include:
- beggarticks (Bidens pilosa)
- cocklebur (Xanthium strumarium)
- longspine sandbur (Cenchrus longispinus)
- puncturevine (Tribulus terrestris)
- Cook, J. Gordon (1968). ABC of Plant Terms. Watford, Herts: Merrow. OCLC 223208923.
- Noogoora burr, Californian burr, Italian cockleburr and South American burr (Xanthium species). New South Wales Department of Primary Industries. 2009.
- History of VELCRO®. velcro.com
- Magee, M. B. Plants With Burrs. San Francisco Chronicle.
- Xanthium strumarium. University of California IPM.
- Cenchrus longispinus. University of California IPM.
- Tribulus terrestris. University of California IPM.
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