The Nutritional and Health Potential of Blackjack (Bidens pilosa l.): A Review – Promoting the Use of Blackjack for Food

Taxonomic Tree

• Kingdom:Plantae

• Subkingdom:Tracheobionta

• Phylum:Spermatophyta

• Subphylum:Angiospermae

• Class:Magnoliopsida

• Order:Asterales

• Family:Asteraceae

• Genus:Bidens

• Species:Bidens pilosa

Characteristics, Favourable Conditions, Growth and Dispersion

Blackjack is said to grow in all seasons in the tropics, most actively in the warmer and wetter parts of the seasons (Holm, Plucknett, Pancho & Herberger, 1977). It is highly resistant to harsh climatic conditions such as drought and cold and it may have a life cycle of 150-360 days. Each blackjack plant has the capacity to produce more than 30000 highly viable seeds. Thus it is possible for blackjack to produce three to four generations per year (Mitich, 1994). Also, blackjack’s seeds are light and spikey, thus they can readily attach to animal skin, machinery or clothing, and in so doing are easily dispersed.

Furthermore, blackjack’s seeds germinate on the soil surface or in shallow soil of 1 - 4 cm depth and at greater depths they remain viable in the soil for many years (Chivinge, 1996). Tilled land, moisture and temperatures at 20, 25 and 30°C are known to favour germination, with 25⁰C being the most favourable temperature at which 70% of seeds were reported to germinate (Chivinge, 1996). The ease with which blackjack is dispersed, and its capacity to produce huge quantities of highly viable seeds provide capacity for blackjack to grow profusely (Figure 2) and to be available throughout the year.

Figure 2.

Blackjack colony