Species Profiles - Vascular Plants
Ferns, herbs, shrubs, vines and trees are known as vascular plants. The current
number of native vascular plant species in PA is 2,151 (Forest Health Plan 2006).
In addition to native flora, non-native vascular plants comprise approximately 41
percent of the flora in PA (Flora of PA, 2006). This means they are established
in the wild outside of minimally managed habitats. Many of these non-native plants
have not demonstrated invasive characteristics (Not Invasive) in
these naturalized populations. Others are clearly invasive in all situations
(Known Invasive ), while still other plants are of great economic
value and importance in a given situation while potentially deleterious (Potentially
Invasive) or highly undesirable in others.
Known Invasive Plants (Widespread): Most of our most common weeds
in Pennsylvania are non-native "invasive" plants that date back to colonial times
and are considered widespread across the state. Other well
known weeds, like mile-a-minute and garlic mustard, are more recent invaders that
quickly spread across the
state. Two of our states' noxious weeds (Canada thistle and Johnson grass) have
been regulated since the 1800's
and many of the weed seeds on the Noxious Seed List date back to colonial times.
Some well known escapes from
cultivation (multiflora rose and asiatic bittersweet) are considered common and
widespread across much of Pennsylvania.
Known Invasive Plants (Limited): Other well known or common non-native
invasive plants in Pennsylvania can be categorized as limited in
the state or in regions of the state. Some well known examples are kudzu, giant
hogweed and goatsrue. Still others like Japanese knotweed, Japanese hops, and tree
of heaven are limited across the state but widespread in certain counties or regions.
Known Invasive Plants (Not Established): Fortunately, some of the
worst plant invaders are not established
in Pennsylvania or even in Northeast but are well known in the South and
in the Midwest. Preventing their establishment by implementing prevention, early
detection and rapid response strategies should be a key
element of the invasive species plan.
Potential Invasive Plants (Widespread, Limited, Not Established):
As previously mentioned, many
non-native plants are purposely grown for cultivation or landscape purposes and
have never shown any deleterious characteristics. Other warm season grasses, forbs
and many aquatics simply cannot reproduce in Pennsylvania
due to our winter climate and short growing season. However, global warming effects
on Pennsylvania resulting
in milder winters year after year and the ability of invasive plants to rapidly
adapt raises the precaution that
criteria should be developed to evaluate the potential invasiveness
of these plants. As many states have done,
the Pennsylvania Invasive Species Council will pursue the development of criteria
in order to determine the potential invasiveness of non-native plants that are not
considered a current problem in Pennsylvania.
* Not known to be established in the wild in Pennsylvania.
** Limited populations discovered in Pennsylvania.
*** Widespread in either a region or across the state of Pennsylvania.
- Species listed above are just some of the species that were mentioned in the various
Council documents published in 2006 and this is not a comprehensive list of invasive
species in this group for Pennsylvania.
- Whenever possible, we have linked to a Pennsylvania specific fact sheet or a federal
See the Pennsylvania Department of Agriculture
Noxious Weed List
Noxious Seed List
for information on weed species that are regulated
For more information on Invasive Species of National concern visit:
National Invasive Species
Information Center website.
¹A single population of tropical soda apple was discovered and eradicated in Pennsylvania
in the 1990's and this species did not become established in the state.