Commercial Native Plant List

Plants on the list meet specific criteria

In keeping with the language and intent of legislative House Bill 950 also known as the Maryland Native Plants Program (MNPP), the Commercial List comprises species that are native to Maryland, sold commercially, and deemed appropriate for residential and commercial landscapes. The Bill defines native plant as a plant that "occurs naturally in the State and surrounding region, ecosystem, and habitat, without direct or indirect human actions. This includes plants that were present before colonial settlement or are listed as native to the State on the Maryland Plant Atlas website."  

How were species selected? An Advisory Committee that includes partners from the MNPP and industry representatives, specifically Maryland growers and retailers, created a list of natives sold then vetted each species. The list has ~650 species and continues to grow as we learn of additional species that meet the criteria above and are sold in the trade. To request additions to the list, please submit the 'add a species' form. Also, per the Bill, the list will be reviewed at least every three years.

Rationale for native plants omitted from the list

The following plant species, though native to Maryland, are excluded from the Commercial Maryland Native Plant List due to one or more of the following:

1.  State status as:
   1. Critically Imperiled/Highly State Rare (S1)
   2. Imperiled/State Rare (S2)
   3. Endangered (E)
   4. Threatened (T)
   5. Presumed Extirpated (SX)
   6. Historical (Possibly Extirpated) (SH)
   7. Endangered Extirpated (X)
   8. Status Uncertain (SU)
   9. Conservation status rank not applicable (SNA)
2. Difficult to cultivate (i.e. propagation or other issues)
3. Possible confusion with non-native species or hybridizes with invasive species
4. Poses health hazard(s)

Additional notes

• Source for #1: Maryland Natural Heritage Program. 2021. Rare, Threatened, and Endangered Plants of Maryland, C. Frye Ed., Maryland Department of Natural Resources, 580 Taylor Avenue, Annapolis, MD 21401. DNR 03-030321-270
• Native species on the excluded list do not count against nurseries and growers, as they are excluded from inventory calculations.
• MNPP discourages the propagation and planting of these species.
• The commercial list may include a particular E/T/S1/S2 species when it is widely available in MD native plant nurseries (e.g., Baptisia australis).                     

Selected plant species are not on the commercial list because they are probably non-native or non-native invasives

Cultivars and hybrids are included on the commercial list only under specific circumstances

Several economically and ecologically important tree species native to Maryland are in peril or functionally extinct due to disease or pests. A few prime examples are American chestnut (Castanea dentata), elms (Ulmus spp.), and beech trees (Fagus spp.). There is a provision in the legislative Bill to include disease/pest resistant cultivars or hybrids of species that are no longer able to fill their ecological role.  

Cultivar is short for cultivated variety, and cultivars of native plant species are sometimes called nativars. Hybrids are deliberately bred or naturally occurring plants created when different species cross during fertilization or when a straight species and a cultivar cross. Often hybrids are lumped in with cultivars, as is done in the rest of this section. Cultivated plants are bred for specific traits such as compactness, bloom and leaf color, longer flowering times, and disease or pest resistance. There is a wide range of cultivar types, from genetically modified strains to natural selections of straight species found in the wild. Their ecological benefits also vary. For example, double flowers are showy, but are mostly devoid of nectar and pollen for pollinators.

On the other hand, cultivars that are selections of naturally occurring wild species can offer desirable aesthetics, while maintaining ecological benefits. Mt. Cuba Center's research program evaluates various performance metrics, including number of visits by pollinators, for straight species and their cultivars. While straight species are the gold standard, many cultivated varieties do well in these trials, making them an attractive option for some landscape applications. Still, there's a lot that we don't know about potential issues with cultivars. Are they good host plants – nurseries for butterflies and moths – especially those plants with redder leaves and stems? How about the nutritional value of cultivars? A lot more scientific research is needed to get answers.

Why aren't naturally selected cultivars included on the commercial list? Cultivars can have negative effects on wild populations. If a particular cultivar cross-pollinates with wild populations, and the genetics cause the new plants to be more susceptible to a particular disease, wild populations of a native species could be reduced or wiped out. In contrast, if a cultivar is more aggressive and cross-pollinates with wild populations, the new plants could reduce biodiversity and damage the ecosystem by crowding out other native plants. Further, the selection and breeding process (usually cloning) can lead to reduced genetic variation. A narrowed gene pool can severely limit a population's ability to adapt to rapid environmental changes, such as more frequent droughts. Thus, per the Bill, the Maryland Native Plants Program focuses on and encourages the use of straight species instead of cultivars.