Xanthium Leaf Movements in Light and Dark

Xanthium leaf movements in light and dark.

Bunning suggested that circadian rhythms provide the basis for time measurement in the photoperiodic responses of plants (2). A classic example is found in Glycine max. L. Merr. (Biloxi soybean), whose flowering response occurs in a rhythmical form having peaks of flowering that were approximately 24 hr apart (6). Recentlv Moore et al. (5) reported that Xanthiuim pensylvanicum did not exhibit a...

The participation of two rhythms in the leaf movements of xanthium plants given various light-dark cycles.

We have shown Xanthium strumarium exhibit two distinct leaf movement rhythms with one occurring in continuous light and presumably related to an endogenous rhythm initiated by the "light-on" signal and the other occurring in continuous dark and presumably related to an endogenous rhythm initiated by the "light-off" signal. Characteristic of the light-on rhythm is a sudden and rapid downward mov...

Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness.

Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO(2) on leaf R during illumination are largely unknown. We studied the effects of elevated CO(2) on leaf R in light (R(L)) and in darkness (R(D)) in Xanthium strumarium at different developmental stages. Leaf R(L) was estimated by using the Kok method, whereas leaf R(D) was measur...

Effect of light intensity and temperature on light-avoiding leaf movements in two Phaseolus species

Aftereffects of low and high temperature pretreatment on leaf resistance, transpiration, and leaf temperature in xanthium.

Leaf resistance for water vapor (total diffusion resistance minus boundary layer resistance), transpiration, and leaf temperature were measured in attached leaves of greenhouse-grown Xanthium strumarium L. plants that had been pretreated for 72 hours with high (40 C day, 35 C night), or low (10 C day, 5 C night) air temperatures. Measurements were made in a wind tunnel at light intensity of 1.1...