Those Ivied Walls

Just a little Gothic: Princeton

The “Ivy League” was originally a sports arrangement, existing unofficially in the 19th century, getting its name in the 1930s and finally coming into formal existence in 1954. The seven of the eight schools included – Dartmouth College, the University of Pennsylvania, Harvard, Brown, Yale , Columbia, Princeton, and Cornell universities – were founded during the Colonial period (Cornell as founded immediately after the American Civil War). Their campuses were indeed distinguished by buildings covered with ivy. There were even annual ceremonies during the 19th century during which ivy was planted next to the walls of academic buildings.

Although the Ivy League is technically a sports agreement, because it was made among the oldest, most prestigious schools in the country the term ‘Ivy League’ has always connoted social elitism and a high standard of academic excellence. At various times Fordham, Georgetown, Rutgers, Syracuse, the University of Pittsburgh, and even the U.S. Military Academy (West Point) and the naval academy (Annapolis) were grouped with what are now considered the canonical eight.

Apparently if a building was covered with ivy, it meant that it had been there for some time and that implies continuity, stability and, by virtue of these characteristics, quality. Perhaps letting ivy grow all over your infrastructure also suggested a certain indifference to worldly concerns.

Hedera helix, English ivy

The “real” ivies, the genus Hedera, are members of the ginseng family, Araliaceae, and they are widespread in Europe, Asia and the “Macaronesia” islands off the coast of Europe and North Africa. Hedera species are evergreen and will grow up any vertical surface was extending aerial roots that attach to the surface. Stone surfaces are actually slowly torn apart by the ivy and it isn’t really a very good maintenance plan to allow Hedera to grow on built structures.

Parthenocissus tricuspidata, Boston ivy

Landscape designers very much discourage the use of Hedera, and instead advocate planting of Parthenocissus species if one desires greenery on a wall, pergola, or arch. P. tricuspidata or Boston ivy is deciduous and attaches to surfaces with small circular pads at the end of tendrils. The pads are glued to the surface by calcium carbonate secreted by the plant. While this makes white deposits across the surface of the building stone or brick, it doesn’t not disintegrate it.

Although called Boston ivy for its ubiquity in that city P. tricuspidata is native to eastern Asia and is not a true ivy, but instead is related to grapes. Its leaves somewhat resemble those attached to grape vines, but they are three-lobed rather than five-lobed. Hedera helix (often called English ivy) has five leaflets on young shots, but has smooth, almost leathery five pointed leaves arranged alternately on mature stems.

Parthenocissus quinquefolia, Virginia creeper

The native Parthenocissus quinquefolia or Virginia creeper has five leaflets and is sometimes confused with poison ivy, which has three. The leaves of both vines turn a brilliant red in the fall before they drop. Like P. tricuspidata Virginia creeper attaches to surfaces with adhesive discs and doesn’t damage structures. Both vines, however, grow rapidly and may become too heavy to be supported by some trellises. Maintenance experts recommend killing the vines by cutting them off at the base. The carbonate on the discs will dissolve after the plant dies, making it easier to remove and preventing damage to the supporting surface.

Hedera gone wild in Maryland

All three of these vines produce berries that are consumed by birds, and this is their primary means of distribution. Hedera actually flowers very late in the autumn and into early winter. The small five-petaled flowers are borne at the end of stiff pedicels that radiate out in all directions from a central stem. The berries are greenish-black and poisonous to humans. Parthenocissus flowers are greenish, small and borne in clusters. Unlike Hedera, it flowers in the spring. The berries are small and bluish, betraying the genus’s relation to grapes.

Hedera is considered an invasive species where it grows in the United States. It is actually banned from the state of Oregon. Because it grows rapidly and is an evergreen, it tends to shade out all other plants, creating ‘ivy barrens.’ Even so, landscapers looking for a low-maintenance ground cover may plant it to fill a space and cut down on their weeding.


Bob’s Your Uncle Sumac

One of the first trees to show signs of the draining of chlorophyll from its leaves in the fall is the sumac. As the excision layer grows across the base of the petiole, cutting off the supply of raw materials for making chlorophyll, the big unstable molecule breaks down, leaving behind the yellow-reflecting carotene and red-reflecting anthocyanins. Sumac leaves would seem to have abundant anthocyanins, as they turn a deep, saturated scarlet each fall.

Staghorn in the fall

The most common sumac in the northeastern United States is the staghorn sumac (Rhus typhina). The leaves of staghorn sumac are pinnately compound and each leaflet is coarsely toothed. It is an early succession species that is common along roadsides and in old fields and clearings. Staghorn sumac is dioecious (separate male and female plants) and the female plants carry clusters of drupes that are collectively referred to as “bobs.” They give the staghorn species its name; R. typhina bobs are particularly dense, erect, resembling a buck in velvet, albeit bright red.

The seeds are eaten and distributed by birds. Once a plant grows from a seed it will often spread vegetatively in every direction from rhizomes. These clonal copses are particularly striking in old fields where they may expand radially in a nearly perfect circle. The plants decrease in size toward the periphery (because they are younger), giving the whole clone the appearance of a leafy dome in the warmer months.


Like many early succession species, sumac grows rapidly, often adding a couple of feet in height during one growing season. The wood is soft, weak and greenish-brown. The central pith in smaller trees and large branches in a punky substance that can be pushed or scraped out with a fingernail. It’s frailty makes the wood commercially useless, but the strong banding of the annual rings gives the wood a striking appearance when it is turned into bowls or carved to make ornaments and tool handles.

Many people are leery of sumac because its similar cousin Rhus vernix, poison sumac, is well known for the nasty rash it imparts upon contact with skin. The “poison” members of Rhus are sometimes placed in their own genus, Toxicodendron, and these include poison ivy (Rhus toxicodendron, or Toxicodendron radicans) and poison oak (R. diversiloba).

In my own experience poison sumac is more virulent than poison ivy. I accidentally touched a poison sumac plant being grown in a botanical garden on the campus of the College of the Atlantic in Bar Harbor, and the reaction was an immediate tingling sensation that lingered for hours even though I immediately drench the hand in cold water from a nearby tap. In contrast, a poison ivy rash may not manifest for hours after contact.

Poison sumac

Luckily, poison sumac is rare, confined to extremely wet areas in swamps, marshes, and along the banks of slow rivers. Although its leaves are also pinnately compound, the fruit is white instead of red and the bobs are not as compact as those of R. thyphina.

The global distribution of Rhus is interesting in that the highest concentration of species are in North America and Africa (rather than on adjacent continents). In the Middle East the bobs of R. coriaria are used to make a spice that is used somewhat like paprika, sprinkled over fish, chicken, and hummus, giving it a tart flavor. In North America, staghorn sumac bobs are soaked in cold water and then squeezed to create a tart liquid. When sugar is added it called “Indian lemonade.” North American tribal people mixed pieces of the drupes with tobacco to create smoking blends.

Because of its impressive fall foliage, architectural manner of growth, and its tendency to rapidly fill a space provided, sumac is sometimes used in designed gardens. The individual flowers are small and greenish-white, but the spikes are several inches long and often abundant on the plant, making an impressive show, especially from a distance.

However, the clonal nature of the growth can cause the plant to become invasive and it is difficult to eradicate once established. Every piece of the clone has to be dug up and removed or growth will resume soon and rapidly.