Interrupting each long night with a prolonged period of far red radiant energy resulted in the inhibition of floral initiation in cocklebur. Irradiations inducing different relative levels of P(FR) from 1 to 2% to 80% had about the same effect under 4-hour photoperiods. The lower levels of P(FR) induced by continuous far red irradiation were not as effective as the higher levels induced by red ...

We have examined the effects of mild, chronic water stress and acute water stress on two water stress sensitive plants, Xanthium strumarium and Helianthus annuus. Using a combination of the leaf disc O(2) electrode to measure the light responses of photosynthesis and 77 K fluorescence to monitor damage to the primary photochemistry, we have found the following: (a) The CO(2) saturated rate of p...

The aim of this work was to evaluate the antimicrobial activity of Xanthium strumarium L. leaf extracts against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and Clostridium perfringens, as well as to investigate the presence of the toxic compound carboxyatractyloside in different plant parts. S. aureus and C. perfringens were more sensitive to non-pola...

Two basic experiments defined a long-day inhibitory effect on Xanthium flowering: the basal half of a single leaf on long day inhibits response of the tip half to a short day; and a long-day leaf inhibits response of a short-day leaf, providing it is between the short-day leaf and a receptive bud (whether above or below the short-day leaf). Five hypotheses were explored with the conclusions tha...

Iron administration to iron-starved cocklebur (Xanthium pensylvanicum) plants causes an increase in the iron content of ferritin fractions extracted from mature leaves. Xanthium plants grown under long days (vegetative stage) have more iron and ferritin than similarly iron-treated plants induced to flower under short day regimes. This first demonstration of ferritin in cocklebur (Compositae) le...

Efeito de métodos de extração de compostos fenólicos de Xanthium strumarium L. e suas atividades antioxidantes. The effect of extraction methods and solvents on overall yield, total phenolic content, antioxidant activity, and the composition of the phenolic compounds in Xanthium strumarium extracts were studied. The antioxidant activity was determined by using 2,2-diphenyl-1-picrylhydrazyl radi...

Xanthium strumarium L. is a member of the Asteraceae commonly used in Cuba, mainly as diuretic. Some toxic properties of this plant have also been reported and, to date, very little is known about its genotoxic properties. The present work aims was to evaluate the potential cytotoxic and genotoxic risk of whole extract from Xanthium strumarium L. whole extract of aerial parts. No positive respo...

Xanthium strumarium L. is a traditional Chinese herb belonging to the Asteraceae family. The major bioactive components of this plant are sesquiterpene lactones (STLs), which include the xanthanolides. To date, the biogenesis of xanthanolides, especially their downstream pathway, remains largely unknown. In X. strumarium, xanthanolides primarily accumulate in its glandular trichomes. To identif...

Fluorescence and thermal imaging were used to examine the dynamics of stomatal patches for a single surface of Xanthium strumarium L. leaves following a decrease in ambient humidity. Patches were not observed in all experiments, and in many experiments the patches were shortlived. In some experiments, however, patches persisted for many hours and showed complex temporal and spatial patterns. Ra...