Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
That is indeed a valid point.
Many of the aquarium plants are indeed invasive in the right environment, such as the milder weather in the southern tier of states, and along the coasts.
Most of the plants come from tropical or subtropical climates, and cannot tolerate freezing, but there are a few plants native to temperate zones, and these can certainly survive a trip through the waste water plant and lodge into local rivers and lakes.
Each state has its list of invasive plants that they do not want to have sold, owned, dumped or entering the state for any reason. Many of these restrictions are based on:
Environment. If one plant crowds out several native species then the animals that depended on those natives for food or shelter cannot survive unless they can use the invasive plant for that purpose. Often they cannot.
Transportation. Many invasives grow so rampantly without the original herbivores/pests/diseases that kept it under control in its native land that the shear mass of plants is blocking shipping lanes, and costing millions of dollars to keep it under enough control that ships can pass.
Water pumping. Water inlets to pumps for drinking, agriculture and industry are usually build with local conditions in mind, so that they take in the lowest amount of local plants and animals. But invasive plants can grow in ways that may block these inlets, and can cause changes in wildlife habits that might encourage them to live closer to a water intake.
Usually the small volume of plants that are shared among aquarium people is not a big concern to the authorities, except for a few plants on the 'most noxious' list.
People who sell plants for ponds are more restricted because ponds are outdoors, and the plants are expected to survive through the winter. Well, if they can do that in a pond, they can do that in the wild, so stores are more carefully monitored about which pond plants they sell.