In some species of mangroves, for instance, the seed germinates and grows from its own resources while still attached to its parent. Seedlings of some species are dispersed by currents if they drop into the water, but others develop a heavy, straight taproot that commonly penetrates mud when the seedling drops, thereby effectively planting the seedling. This contrasts with the examples of vegetative reproduction mentioned above, in that the mangrove plantlets are true seedlings produced by sexual reproduction.