The AV node receives the impulse from the internodal pathways, delays it by approximately 0.09 seconds and the impulse passes through the AV bundle which delays it for a further 0.04 seconds. The AV node and bundle is able to achieve this delay by slowing the conduction of the electrical impulse. The gap junctions between successive cells of the AV node and bundle fibers are fewer which therefore increases the resistance to the impulse.
There are now reblooming iris available that rebloom in the fall. The rebloomers can be divided in the same way as the one-time bloomers. The best time to plant or transplant iris is after flowering through August. Iris are one of the few perennials to transplant during the hottest part of the year. Established plantings of iris should be divided every 3-4 years or whenever the clump becomes crowded or when flowering decreases.
How do I dig, divide, and transplant bearded irises? Bearded irises can be divided any time after your last frost date in the spring, but many irisarians believe the optimal time to divide them is 6-8 weeks after bloom.