Chicago Botanic Garden’s perennial breeding program takes a different approach from most commercial programs, according to Justin Lombardoni, the Garden’s ornamental plant breeder. Speaking at the Perennial Plant Association’s National Symposium in East Lansing, Michigan, in July, Lombardoni said the non-profit program prioritizes native plants, focuses on niche genera and avoids traits that can reduce a plant’s ecological function.
Lombardoni said he believes the Garden’s program is the only breeding program at a botanic garden in the country. Because it operates within a non-profit institution, he said, it can target different genera and traits than for-profit breeders. Native status is a priority, though not an absolute requirement. Lombardoni prefers a regional definition of native status over county or state boundaries, arguing that plants do not recognize artificial borders, especially where no physical barrier prevents spread.
For non-native genera, the program evaluates two seed-related factors that can contribute to invasive potential: fecundity, or how much seed a plant produces, and dispersal, or how readily those seeds spread. Vegetative spread through rhizomes, stolons, suckers or other non-seed means is also considered. Lombardoni cited kudzu (Pueraria montana) as an extreme example of what can happen when a plant’s ability to spread is underestimated.
The program concentrates on niche genera rather than mainstream ones. Lombardoni said its small size and limited resources make it unable to compete directly with larger commercial breeding programs. Even if it could, he added, many mainstream genera already have dozens or hundreds of cultivars on the market. He questioned whether the market needs another Echinacea or Hosta when comparatively esoteric genera still have untapped potential.
Traits vary by genus, but Lombardoni identified two categories the program does not actively pursue. One is highly compact cultivars, which have become common in commercial breeding because they look good in pots and ship efficiently. Lombardoni defined compact in this context as about 30 inches or shorter. He distinguished that from merely reducing the size of an unruly species, saying a 4-foot cultivar bred from a species normally 5 or 6 feet tall would not qualify as very compact. The other category is sterility, including “double” flowers in which extra petals may replace pistils or stamens and reduce available pollen or make floral resources less accessible to pollinators. More broadly, he said, the program does not seek traits that hinder ecological function.
Pollinator support is a priority for many home gardeners, and Lombardoni said the Garden hopes to collaborate with its Science Department, which is partnered with Northwestern University, to study pollinator visitation to breeding selections. The work would compare visitation to the selections with visitation to straight species, helping the program understand differences in abundance and diversity of pollinators. That collaboration is a goal rather than a completed study.
One cultivar that reflects the program’s priorities is Eutrochium maculatum ‘Summer Snow’, released about 10 years ago. It was bred from germplasm collected roughly 90 miles from the Garden, in a location three counties away. Lombardoni still considers it a native selection because the species is native to the Garden’s county. The cultivar reaches about 5 feet tall, not significantly shorter than the straight species, and its upright stems bear white flowers from mid- to late summer that support pollinators.
Lombardoni said aesthetics are a major consideration in breeding perennials for the commercial market, especially how a plant looks in a pot, while ecological function may not always receive the same emphasis. Because the Chicago Botanic Garden is a non-profit, he said, its program is not trying to release a set number of cultivars each year or maximize sales of each one. That lack of pressure, he said, allows it to breed perennials differently from many commercial programs. He added that he hopes gardens will not someday consist entirely of perennials 2 feet or shorter.