Yardsmart: Botanical immigrants

For centuries, immigrants from all corners of the world have flooded into the United States. Yet many people don't realize there have been other — more silent — visitors that have come to our shores to take up residence just as people have. And some of these "botanical immigrants" have proved highly capable of adapting to our regions. When a new plant lives happily on our native soil, we know that it will be just as willing to enrich our own gardens today.

You can spot them in rural areas and declining urban neighborhoods. They spring out of broken sidewalks, cluster in the shade of abandoned buildings and bloom their hearts out beside windowless farmhouses. Though the original human immigrants have gone, the plants they knew and planted often remain as a testament to history.

It's called naturalizing, when a plant becomes established in a new locale for an indefinite time period. Do not confuse these with invasive exotics, which are plants that don't just naturalize but go on the road, invading the whole countryside with their vigor. They are classified as expansionist armies, and not the peaceful immigrants that have become mainstays of earlier American gardens.

Here in California, we see German irises out in pastures where once a farmhouse stood. In the mountains, a solitary lilac thrives in the cold of high altitude, once cultivated by a rancher's wife who has long since passed away. Even a fruit tree with its spring haze of blossoms may live long after a homesteader went back home, attesting to its adaptation to soils, climate and rainfall.

These immigrants offer an exceptional palette for first-time gardeners facing less-than-ideal conditions, much like pioneers did well over a century ago. If you can gather the seed, dig a root or take a cutting, you can grow a survivor in your own home. Learning how to propagate plants and use them for food or decoration is a wonderful hobby in hard times.

German irises grow close to the surface of the soil with thick tuberous roots that end in shoots of bladed foliage. To propagate these, simply break off segments, bring them home and plant shallow where soils are resistant to deeper rooting. Further south, the iris that would become the progenitors of today's Louisiana iris can be found around homes throughout the South. They are exceptionally valuable to low-lying areas that have poor drainage.