Dispersal is consequently limited to the usually short distance that the animals can carry the seed. Cycas subsection Rumphiae has seeds with a spongy endocarp not seen elsewhere among the cycads, which gives a potential for oceanic dispersal, and it has been demonstrated that seeds maintain viability after prolonged immersion in sea water. There are few living survivors, and fossil records date back to over 250 million years old. As such, cycads have great intrinsic interest, both to the scientific community and to the general public, as a survivor from eras long past, and as a possible window on life in those times. Cycads are of cultural and religious significance to many different peoples around the world.
Cycads have considerable economic importance in horticulture.
Cycads contain unique and potent toxic compounds that have caused problems to people and livestock in contact with them, and are of interest to the pharmaceutical industry. The cycads are the sister group to all other extant seed plants. An understanding of the evolution of the cycads is important in understanding the evolution of all modern plants. Cycads fix atmospheric nitrogen, important in maintaining health and fertility of soils. The fixation mechanism is through a cyanobacterial symbiosis that is unique to the cycads.