Seed Discharge in Arceuthobium: A Photographic Study
Photographs, made at a speed of 5 microseconds, of the ejection of the Arceuthobium seed from its fruit, show that tumbling in the vertical plane begins soon after discharge and that most seeds have turned 90 degrees when they have traveled about 6 centimeters. As the seeds leave the fruit they have a viscous sheath around the trailing end that disintegrates after the seeds have traveled about 2 to 3 centimeters. This viscous material does not act as a rudder as has been postulated.
Snap, crack and pop of explosive fruit.
There is an increasing appreciation for the role of physical forces in plant development. Mechanics are fundamental to how explosive fruit eject their seeds, and recent studies have successfully combined mechanics with developmental genetics to help explain how these dispersal traits are produced and how they evolved. Computational modeling is used more and more to address developmental questions, and explosive fruit are particularly good systems for combining biology and modeling approaches. Finite element models have been recently used to explore questions such as: Why do touch-me-not species with similar fruits, differ so much in how efficiently they transfer stored energy to eject seeds? And how do popping cress fruits use the expansive force of turgor pressure for tissue contraction?
The Mode of Action of Aldrin and Dieldrin in Periplaneta Americana (L.)
Although aldrin and dieldrin have been widely used as insecticides for several years, little significant information has been developed concerning their mode of action in insects. It is the purpose of this paper to develop information in this regard, particularly as to their comparative toxicities, sites of toxic action, and metabolism in the American cockroach, Periplaneta americana (L.).