Tree of Heaven

What’s blooming in the area: Apples, iris, moss phlox, donkey tail spurge; lawns and hay fields beginning to green near road where water flows from ditches.

Beyond the walls and fences: Choke cherry, fernleaf globemallow, cheese mallow, western stickseed, bractless cryptantha, hoary cress, tansy and tumble mustard, alfilerillo, bindweed, gypsum phacelia, purple mat flower, goat’s beard, native and common dandelions, June and cheat grass; buds on Virginia creeper; milkweed and ragweed coming up.

In my yard: Sour cherry, spirea, Siberian pea tree, lilacs, tulips, grape hyacinth, baby blue iris, vinca, yellow alyssum, oxalis, small-leaved saponaria, blue flax; buds on snowball, peonies and Bath pinks; tomatillos coming up.

Bedding plants: Pansy, sweet alyssum.

Inside: Pomegranate, zonal geranium, aptenia, asparagus fern.

Animal sightings: Hummingbird and bumble bee on Siberian pea; smaller bees around lilac; harvester and small black ants.

Weather: Rain early Monday and Tuesday mornings, followed by cooler nights and more winds; snow remains in Sangre de Cristo; 14:32 hours of daylight today.

Weekly update: There’s something worse than a Siberian elm. Trees of heaven not only produce viable seeds and resprout when pruned like elms, but they also sucker from their roots into copses and exude chemicals that keep other plants from their territory.

The team writing the environmental impact statement for widening the road from Española to Los Alamos on the other side of the river found Alianthus altissima growing around Santa Clara creek and recommended it be eradicated as a class B pest. Siberian elms are only class C nuisances and so not proscribed by the state. They can, however, be destroyed during construction without penalty.

Trees of heaven have gotten started along one of the village ditches at the northern end where water from the Santa Cruz enters the acequias. In one area, they’re competing with Siberian elms between the ditch and the pavement. This past winter both were cut back to keep the narrow road clear, but neither was fazed. One is bright green with new leaves. With last week’s warm weather, the other was beginning to leaf at its branch tips.

Ch’un shu is known in China as the spring tree because it’s one of the last to break dormancy, and thus signifies the end of winter famine. According to Shiu Ying Hu, it was primarily used for cooking fuel. However, the dried bark removed from felled trees could also be sold in markets for medicinal purposes as ch’un-po-pi.

The tree entered the western world under false pretenses. A French Jesuit priest, Pierre d'Incarville, thought he was sending back seeds of the tree the Chinese used to make lacquer. When they germinated in Paris, the saplings were mistaken for sumac, because the long leaves broken into pairs of smaller leaflets were similar.

William Prince introduced it commercially in this country as Sicilian Tanner’s Sumac, after Archibald Thompson sent him plants under that name from his West End nursery outside London. Once Prince realized the confusion and offered it as Chinese Ailanthus in the 1820's, the tree began to sell so well his Flushing nursery had problems meeting the demand because he only had male trees. They’re more floriferous than the females and the taller form was considered more aesthetically pleasing.

The market had already been created in Paris where American visitors saw Grand Vernis du Japon growing along the boulevards, especially on the left bank in the fifth arrondissement of Montparnasse. In those years of early industrial life, when coal was burned to produce steam and heat homes, the air was polluted with soot that killed many species. Insects attacked others. The fact the five-petaled male flowers smelled didn’t matter when horses were used for transport.

By the 1840's, Andrew Jackson Downing, the primary popularizer of romantic landscapes in this country, noted the Celestial Tree was “much planted in the streets and public squares” of New York and Philadelphia and that it was especially picturesque on lawns where “the foliage catches the light well, and contrasts strikingly with that of round-leaved trees.”

The tree grows rapidly its first years, concentrating its efforts on height. After about five years it begins to branch. After ten to twenty years, the females produce seeds. Then, home owners discover the problems with seeds, suckers and the smells they released when gardeners try to remove them. By 1851, Downing had turned against the grey barked tree and was recommending “graceful elms and salubrious maples” for street use.

However, a hundred years later Rosalie Doolittle was still telling Albuquerque gardeners that, despite its “reputation for being untidy,” a tree of heaven was “really attractive when the sprays of pods turn brilliant red and yellow as falls approaches.” Even a few years ago Baker Morrow advised New Mexicans the much maligned tree “can make a very pleasant shade or street tree in the right setting.”

They’re correct the tree is attractive when allowed to grow naturally into a wide, low canopy. Both males and females are covered with yellow-green flowers at their branch tips in late spring. Then, in late summer, pink seed heads appear above the leaves, resembling mimosa from a distance.

In Santa Fe, I’ve seen trees growing in courtyards shading working class homes built in the 1950's. Although they tolerate a wide variety of soils, the strong tap roots prefer the lime rich soil of the area. Unfortunately, they need more water than the arid west provides, a minimum of 14" a year, and so they send out suckers to the water conserving yard walls and foundations. Seeds, and possibly discarded suckers, found their way into the nearby ditch, neglected since it was no longer used for irrigation.

Here, trees of heaven not only are growing along the ditches and road sides, but it looks like the member of the tropical simaroubace family has been planted deliberately by a few people, probably from free suckers. In one place down the road, a mature tree shading a double-wide deflected a flying seed, and now has a Siberian elm sapling amongst its suckers.

Notes:
Doolittle, Rosalie. Southwest Gardening, 1953, revised 1967.

Downing, Andrew Jackson. A Treatise of the Theory and Practice of Landscape Gardening, 1841.

_____. “How to Popularize the Taste for Planting,” The Horiculturalist 7:297-301:1852, quoted by Behula Shah in “The Checkered Career of Alianthus altissima,” Arnoldia 53(3):21-27:1997.

Gannett Fleming West, Inc. NM 30 Improvement Project, Environmental Assessment, January 2011.

Hu, Shiu Ying. “Alianthus,” Arnoldia 39(2):29-50:1979 .

Morrow, Baker H. Best Plants for New Mexico Gardens and Landscapes, 1995.

Murrill, William A. Shade Trees, 1902; on use in Paris.

Prince, W. R. “Introduction of Lombardy Poplar,” The Gardener's Monthly and Horticultural Advertiser 3:80:1861; on his father’s activities.

Photograph: Tree of heaven leafing along a ditch near the village already colonized by bright green Siberian elms, 24 April 2011.