The Three Sisters—or Is it Four?

(An excerpt from Gaia’s Garden)

Let’s begin our exploration of guilds (communities of plants for the garden) with a very simple example that illustrates some essential principles. Then we can proceed to more complex guilds—ones that go beyond vegetables.

Familiar to many gardeners is the Native American triad of corn, beans, and squash, a combination often called the Three Sisters. The trio qualifies as a guild because each of these plants supports and benefits the others. The cornstalks form a trellis for the bean vines to climb. The beans, in turn, draw nitrogen from the air, and via symbiotic bacteria convert the nitrogen to plant-available form. These nitrogen-fixing bacteria, scientists have recently learned, are fed by special sugars that ooze from the corn roots. The rambling squash, with its broad leaves, forms a living parasol that densely covers the ground, inhibiting weeds and keeping the soil cool and moist. Together the Three Sisters produce more food, with less water and fertilizer, than a similar area planted to any one of these three crops in isolation. Jane Mt. Pleasant, an agronomist at Cornell University who has blended her Iroquois heritage with her research, has shown that yields of this guild, measured in calories, are about 20 percent higher than corn grown alone in an equal-sized plot.

Look at how many interconnections this guild bears. Beans furnish nitrogenous fertility for themselves, corn, and squash; squash shades soil for the benefit of all three; corn feeds the bean-hugging bacterial nodules and creates a trellis for the beans. Three plants, weaving at least eight connections. The Three Sisters guild is a perfect place to begin creating a richly connected garden.

In the Southwest, a fourth “sister” is found in this guild: Rocky Mountain bee plant (Cleome serrulata). Often growing near former Anasazi settlements—it’s virtually an indicator plant for ancient ruins—this 2- to 5-foot tall, pink-flowered cleome is a powerful attractant for beneficial insects that pollinate beans and squash. The young leaves, flowers, and seed pods of bee plant are edible, and native people boiled and ate them, or made a paste from the plant for later use. Bee plant also accumulates iron, and thus is the source of a deep-hued paint used to create the characteristic black designs on Anasazi pottery. Songs and blessings of New Mexico’s Tewa people mention corn, beans, squash, and bee plant, indicating that this multi-functional flower is an integral member of a sacred plant pantheon.

I was pleased to learn of this fourth sister, as it connects the web of this guild’s beneficial interactions with the insect realm. Part of the strength of corn/beans/squash comes from its tie-in with a non-vegetable domain: that of the symbiotic nitrogen-fixing bacteria carried by the beans. And now, by adding a fourth plant to the guild, the web’s pattern strengthens further, drawing insects into the network. Lured by bee plant, these nectar-slurpers will pollinate the squash and beans (corn is wind pollinated), ensuring good fruit set. By extending the three sisters, we’ve moved into three kingdoms: animal, plant, and bacterial. Creating this connectedness allows us to draw upon three billion years of life’s wisdom for aid. A typical apple-centered guild. Below the apple tree, a ring of attractive and grass-suppressing bulbs encloses flowering and food-producing plants that also provide mulch and habitat for beneficial insects. The apple tree is nurtured by this community of multifunctional plants making less work—and more food and flowers—for the gardener.

The lesson here is that by hooking into the cyclical rhythms of many-kingdomed nature, a guild can capitalize on enormous sources of energy and experience. Focusing only on food plants sucks fertility from the soil while giving little in return. In contrast, offering a little something extra—a habitat for bees, a home for soil organisms—ties the small cycles of our garden into the generous and large cycles of nature. Growing a few early-blooming flowers encourages bees and other beneficial insects to stick around when the fruit trees need pollination and the aphids begin to swarm. Leaving last fall’s leaves to compost on a flower bed nurtures a healthy crop of worms to till and aerate soil and to shed nutrient-rich worm castings down among the roots. Our small offerings bring large rewards. In effect, if we buy the first round of drinks, nature picks up the tab for dinner and a show. We can leverage our assets into a not-so-small fortune by piggy-backing onto the pooled resources of the natural economy. By making nature our partner, our yields multiply, and risk of failure declines.

The addition of bee plant boosts the three sisters into a more powerful foursome. This illustrates a useful rule for guild design: Start with something known and basic, and gradually add connections. We now have a hint about creating our own guilds. Let’s see how a more complex guild is constructed, and then we can develop more guidelines for building our own.

Copyright © 2001 by Toby Hemenway

Selected Excerpts from Gaia’s Garden: