First, Some Definitions
A native plant is one that was growing in a particular area before the arrival of Europeans and is very well adapted to that area. A non-native plant is one that was brought into an area and has become established. In Pennsylvania, out of approximately 3,400 plant species, there are over 2,100 native species and about 1,300 non-native species. Native plants in Pennsylvania include trees, shrubs, vines, ferns, grasses, flowering perennials, annuals and biennials. An invasive species is one that grows aggressively and displaces other plants from an area. Sometimes a native species can become invasive when its environment is disturbed. Usually, however, invasive plants are plants from other continents that were introduced into this country either accidentally or deliberately. Other names for non-native invasives are alien, exotic and introduced invasives. For example, multiflora rose (right) was imported from Japan to form barriers along roadways. In its native country, multiflora rose was not a problem because of the natural environmental, pest and disease controls. Introduced into a new environment, it grew malignantly, threatening native plant and animal habitat. Other examples in Pennsylvania are kudzu, purple loosestrife, garlic mustard, Japanese honeysuckle, Japanese knotweed, and oriental bittersweet. Invasives are difficult and expensive to control.
What Can You Do?
Fortunately, there are things we can do to protect our remaining native plant species. One is to learn more about native and non-native invasive plants. Google for information online. Protection of native plant communities and minimizing habitat destruction are imperative for native plant conservation. That includes not removing native plants from the wild to plant in your gardens. To landscape with native plants buy nursery-propagated native plants, and never introduce invasive plants into your garden.
Two Native Plants Found in NFP: Inkberry Holly and Winterberry Holly
Inkberry holly (Ilex glabra) and Winterberry holly (Ilex verticillata) are found in Norristown Farm Park as well as in many of our yards. These plants are easy to identify even in the winter because of their berries. They grow well in our area because they are well adapted to our environment in Zone 6 according to the U.S. Department of Agriculture Hardiness Zone Map.
Inkberry holly (also known as gallberry) has the evergreen leaves as expected for a holly and black berries that persist throughout the winter. There may be a purple cast to the leaves in winter. White flowers appear early in the summer. This plant grows in acid or basic soils, in dry or wetter soils and likes full sun or moderate shade – very accommodating!
Winterberry holly (also known as black alder, false alder and fever bush) is deciduous, that is, sheds its leaves in the winter. The loss of green foliage in the winter is offset by the appearance of bunches of red berries that brighten up the desolate winter landscape. The exuberant red berry display is not only attractive to humans but also to songbirds, game birds, small mammals, and, unfortunately, deer. Flowers appear in the late spring or early summer and are white and very small. Even though the winterberry holly usually grows in wetlands, it is easy to grow inmost garden soils. This holly prefers acidic soils, but is not fussy about light, growing well in full sun or partial shade.
One last note: both these hollies are dioecious. This means there are male and female plants. The male plant is necessary for pollination and the resultant berries on the female plant.