Tree of heaven or hell?

Home - Santa Fe Real Estate Guide - - THEMASTERGARDENERS - SARAH BALD­WIN

Here in the high desert, gar­den­ers and na­ture lovers learn to re­gard al­most any­thing that grows well on its own with re­spect and ad­mi­ra­tion. But there are ex­cep­tions. When a non-na­tive plant is so adapt­able that it spreadswith aban­don, suck­ing up nu­tri­ents and wa­ter and crowd­ing out less ro­bust species, it threat­ens na­tive habi­tats and is a nui­sance in gar­dens: it be­comes “in­va­sive.”

Santa Fe has its share of in­va­sive trees, no­to­ri­ously Siberian elm, but also Rus­sian olive, salt cedar (or tamarisk), and the ul­tra-ag­gres­sive tree of heaven, Ai­lan­thus al­tissima. Like many in­va­sive species, ai­lan­thus was in­tro­duced as an or­na­men­tal be­fore its less de­sir­able fea­tures be­came ap­par­ent. Some­times called “stink tree,” this na­tive of China was brought to the United States via Europe in 1784 and soon es­caped cul­ti­va­tion. It looks a lot like our na­tive sumac, but its flow­ers and leaves emit a fetid odor, un­like those be­long­ing to the Rhus genus.

Tree of heaven is fast-grow­ing, quickly shad­ing out other plants. Though an in­di­vid­ual spec­i­men is rel­a­tively short­lived, ai­lan­thus is very dif­fi­cult to con­trol be­cause it spreads not only by seeds but also by root sprouts, clones of the­mother tree that pro­long its life in­def­i­nitely. It’s seen in weedy colonies along road­sides and in Santa Fe neigh­bor­hoods.

Ai­lan­thus’ tol­er­ance of ex­tremely poor soils and to­tal ne­glect has earned it the nick­name “ghetto tree” in places like Detroit, where it’s of­ten the only thing flour­ish­ing in the rav­aged ur­ban land­scape. De­pend­ing on the sit­u­a­tion, that tough­ness can be virtue. In Betty Smith’s clas­sic novel A Tree Grows in Brook­lyn, a tena­cious tree of heaven grow­ing in con­crete serves as the cen-tral metaphor for sur­vival in ad­verse cir­cum­stances.

I have an am­biva­lent re­la­tion­ship with the tree of heaven on our prop­erty. On the one hand, it re­quires no ir­ri­ga­tion and shades our west-fac­ing drive­way, keep­ing our cars cooler in summer. It also adds care­free green­ery to the street scene. On the other hand, it sends shoots far and wide, through ju­niper bushes and un­der other trees. If I didn’t stay on top of pulling these shoots, we’d soon be in a tree-of-heaven jun­gle.

I asked Bob Pen­ning­ton of Agua Fria Nurs­ery what he would do if he were in charge of Santa Fe’s ur­ban for­est. He said he would at­tempt to erad­i­cate the species. The only way to do that is by cut­ting down the trees and im­me­di­ately poi­son­ing the stumps; the best time to do so is in early fall, when plants are draw­ing in nu­tri­ents be­fore go­ing dor­mant. Even then new shoots may ap­pear in spring.

The peo­ple at Plants of the South­west of­fered a dif­fer­ent per­spec­tive. They sug­gested prun­ing the trees for for­mand cut­ting back the shoots. They also pointed out that if all the tree of heaven and Siberian elm trees dis­ap­peared, Santa Fe would lose a huge por­tion of its cool­ing green canopy.

I some­times re­gard our tree of heaven with a mur­der­ous eye. But in a desert cli­mate that’s get­ting hot­ter, we may need to start mak­ing peace with the weeds that can tough it out.

Sarah Bald­win is a free­lance ed­i­tor, a writer, and a gar­dener.


Leaves and seeds of the “tree of heaven”

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