Conyza canadensis (L.) Cronquist Canadian Horseweed

Conyza canadensis (L.) Cronquist - Canadian Horseweed

Scientific Description:

Stems 30−100 cm, sparsely setulose-hirsute. Leaves narrowly oblanceolate, 3−7 × 0.2−1.2 cm, attenuate at base and acute at apex, entire or with 2−3 shallow teeth on each side, sparsely setulose-hirsute especially at margins. Involucre c. 5 mm broad; phyllaries linear-lanceolate, 1.5−3 × 0.25 mm. Female flowers c. 25; basal tube c. 1.75 mm, ligules white or purplish, 0.75 mm. Hermaphrodite flowers c. 5; corollas 2.5 mm, 4-lobed. Achenes 1−1.25 mm, sparsely puberulous. Pappus brownish-white, 2.5−3 mm.

 

Flowering time: July−December.

Habitat: In moist conditions, often near sea coasts and weed of cultivation, s.l.−1300 m.

 

Reference:
Grierson AJC (1975). Conyza canadensis (L.) Cronquist, In: Davis PH (ed.), Flora of Turkey and the East Aegean Islands, Edinburgh University Press, Edinburgh, 5: 132.

Public Description:

Conyza canadensis, known as “Canadian horseweed”, is distributed in North America and temperate regions of the world. It is an invasive species and has spread across many parts of the world. It is an annual herb with white flowers, and grows up to 100 cm in length. It blooms between July and December and is found in moist conditions, often near sea coasts and weed of cultivation. Because it is resistant to herbicides, it is a very problematic plant on production fields. Skin contact with the plant can cause dermatitis in some people.

 

References:

Anonymous 1 (2016). https://en.wikipedia.org/wiki/Conyza_canadensis/, Accessed date: 07.01.2016.

Anonymous 2 (2016). http://www.db.weedyconnection.com/fleabane-conyza-spp/, Accessed date: 07.01.2016.

Ekim T (2012). Conyza Less., In: Güner, A., Aslan, S., Ekim, T., Vural, M. & Babaç, M.T. (eds.), Türkiye Bitkileri Listesi (Damarlı Bitkiler). Nezahat Gökyiğit Botanik Bahçesi ve Flora Araştırmaları Derneği Yayını. İstanbul, pp. 146.