In Connecticut, plants must demonstrate nine specific criteria to be listed on the state’s list of Invasive Plants. These criteria are defined in Sec. 22a-381b of the CT General Statutes as follows:
(a) In publishing and updating the list of invasive plants required under section 22a-381a, the Invasive Plants Council shall determine that a plant possesses the following characteristics before it is included on such list:
(1) The plant is nonindigenous to the state;
(2) the plant is naturalized or has the potential to become naturalized or occurring without the aid and benefit of cultivation in an area where the plant is nonindigenous;
(3) under average conditions, the plant has the biological potential for rapid and widespread dispersion and establishment in the state or region within the state;
(4) under average conditions, the plant has the biological potential for excessive dispersion over habitats of varying sizes that are similar or dissimilar to the site of the plant’s introduction into the state;
(5) under average conditions, the plant has the biological potential for existing in high numbers outside of habitats that are intensely managed;
(6) the plant occurs widely in a region of the state or a particular habitat within the state;
(7) the plant has numerous individuals within many populations;
(8) the plant is able to out-compete other species in the same natural plant community; and
(9) the plant has the potential for rapid growth, high seed production and dissemination and establishment in natural plant communities.
(b) In publishing and updating the list of potentially invasive plants required under section 22a-381a, before including a plant on such list the Invasive Plants Council shall determine that a plant: (1) Possesses each of the characteristics set forth in subdivisions (1) to (5), inclusive, of subsection (a) of this section; and (2) possesses at least one of the characteristics set forth in subdivisions (6) to (9), inclusive, of subsection (a) of this section.
(c) Upon a finding that a plant meets the criteria for listing as an invasive plant under subsection (a) of this section, or as a potentially invasive plant under subsection (b) of this section, prior to listing such plant as invasive or potentially invasive, as applicable, the majority of the council’s membership shall approve of such listing. On the request of two or more members of the council, the council shall hold a meeting, open to the public, not later than thirty days prior to the publication of the initial invasive plant list or the addition of any plant to the invasive plant list, as applicable.
(d) In listing a plant as invasive or potentially invasive, the council may make recommendations on how to discourage the sale and import of such plants in the state and identify alternative plants to the listed plant for growing purposes.
A summarized, printable version of the criteria for listing an invasive plant in CT is available here.