A noxious weed in the United States, Common Teasel (and Cut-leaf Teasel) is originally from Africa and Europe. It arrived during the 1700’s and is now common alongside roads and disturbed areas. This monocarpic species begins with basal leaves but bolts upwards typically during the second year. Many insects and small invertebrates become caught in the “cups” between the leaves and stem, allowing it to absorb more Nitrogen and Phosphorus (possibly a form of partial carnivory?).
Dipsacus fullonum (Common Teasel, Fuller’s Teasel) [synonym D. sylvestris]
Subspecies: subsp. fullonum, sylvestris
Native: Europe, northern Africa, temperate Asia
Hardiness Zones: 4-8
Height: to 2m
Diameter: to 70cm
Root System: shallow taproot (60cm tall, 3cm wide) with extensive lateral roots, yellow
Growth Rate: moderate to fast, pioneer species in disturbed areas, not a climax species
Age: typically biennial, rarely to 4 years
Tolerates: heavy clay soils,
Problems (major): none
Problems (minor): These are noxious weeds in many regions of the United States of America but are intolerant of thick shade.
Soil requirements: tolerates sandy, loamy, clay, and hard clay soils, prefers moist and rich sites
Air requirements: air pollution
Watering requirement: low to medium; typically in moist, meric habitats, sometimes xeric (dry) conditions
Sun requirement: full sun to part sun
Leaves: initially basal before bolting; basal with rounded serrations, oblong-oblanceolate; non-basal opposite, white midvein, stem-clasping (13cm deep space between leaf and stem, water collection, possible carnivorous or simply retrieves nutrients from drowned, decaying insects and small invertebrates), entire, toothed-wavy margins (pinnatifid in D. laciniatus, Cut-Leaf Teasel), 30cm long by 8cm wide
Stem: robust, hollow, erect, spiny
Flower structure: egg- or cone-shaped inflorescence (1-35 per plant), prickly bracts underneath curve upwards, 250-1500 flowers (each lasting 1 day), perfect, protandous (pollen release before stigma receptive), purple (white in D. laciniatus), self-fertile
Flowering frequency: monocarpic (usually at end of second year), April-October
Fruit type: possibly exceeding 3,000 seeds per inflorescence, to 34,000 for an extremely healthy and well-pollinated adult
Fruit dispersal: typically within 1.5m (dropping, rolling), water (viability remains up to 22 days floating), humans or other animals, not by wind
Seeds require stratification: no (although a short, cold dormancy period promotes germination), quick to germinate and lose viability
Subterranean storage organ: taproot
Annual/Biennial/Perennial: biennial or short-lived perennial
The egg or cone-shaped inflorescences on these have spiny bracts underneath curving upwards. The flowers are purple on Common Teasel and extremely prolific seed producers. The cup-shaped region which catches water may also trap insects. It is believed that these may be a form of partial carnivory or simply a mechanism to retrieve nutrients from decaying animals.
These were previously used for medicinal purposes or to tease certain fabrics/cotton apart.
All of the images provided were taken by me. They may be used for educational/informational purposes only, provided that this article/online journal is appropriately cited first.