There are cases of other plants that will pull themselves down. I know the Australian cycad Macrozamia will reach maturity with 4' long leaves and never produce a stem because it is growing deeper and deeper into the ground each year. I have been to to prevent this and to get a tall stem on the plant to place a piece of flagstone, concrete or other large solid object under the plant before planting. I have noticed quite large roots (contractile as describd by Alberto) on seedlings of Herbertia and Gelasine spp. I have just transplanted these seedlings (2 years old now) and those roots are gone in the pots. I planted the same spp. in the open ground and will do a little digging around to see if they are still at the 2" depth I planted them (with contractile roots) or if they are much deeper now. John Ingram in L.A., CA. http://www.floralarchitecture.com/ "Your Clivia Connection" john@floralarchitecture.com 310.709.1613 (cell, west coast time, please call accordingly. Thank you)