Green Roofs - Living Architecture Monitor - Winter 2009 - (Page 17) NATIVE PLANTS USED Trumpet honeysuckle (Lonicera sempervirens) Crossvine (Bignonia capreolata) Evening trumpetflower (Gelsemium sempervirens) American bittersweet (Celastrus scandens) Virginia creeper (Parthenocissus quinquefolia) Trumpet creeper (Campsis radicans) Pipevine (Aristolochia macrophylla) Crossvine (Bignonia capredata) is an early spring nectar source for hummingbirds and butterflies. American bittersweet (Celastrus scandens) provides berries for birds in the fall and early winter. Virginia creeper (Parthenocissus quinquefolia) attracts fruit-eating birds through the winter and its leaves provide caterpillar food for the Virginia Creeper Sphinx moth. Evening trumpetflower or Carolina jessamine (Gelsemium sempervirens) has nectar for insects and seeds for songbirds. Pipevine or Dutchman’s pipe (Aristolochia macrophylla) offers nectar to butterflies and is a food source for the caterpillars of the Pipevine Swallowtail butterfly. Lastly, Trumpet creeper (Campsis radicans) attracts hummingbirds and is a good soil stabilizer. As valuable as the green wall is as vertical habitat, its aesthetic value cannot be overstated. Starting in late March, when the pinkish orange flowers of Crossvine grace the wall, till late fall when the orange berries of American bittersweet appear, the wall is ablaze with color. Each month brings a new hue of blossoms or foliage, and the changes are not lost on National Wildlife Federation employees or visitors. Bimonthly nature walks offered by Craig Tufts – nwf’s long-time chief Naturalist and guiding force in choosing the vines for the trellis – educate interested staff members about the plants on the trellis, in the meadow and in the surrounding woodlands. WATER SUCKING VINES At present, many of these green wall vines reach up to the third (highest) floor of the building. The green wall plants leaf out in the spring and serve to shade the building during the warmer weather. In the fall, they lose their leaves, allowing for passive solar heating during the cooler weather. “Unfortunately, it’s impossible to measure the energy savings produced by the trellis and the plants,” says Steve Johnsen, nwf’s building manager. “nwf has instituted several energy-saving measures since we moved into the building, and our energy usage varies so much according to the severity of the winter or sumLIVING ARCHITECTURE MONITOR WINTER 17
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