Forest or classroom?It’s both at Heritage Farm!

Megan Henderson, a student in Luther College’s Biology 365 class, examines leatherwood at Heritage Farm. Photo by Beth Lynch.

It should come as no surprise that there are fields, heirloom plants, and rare seeds aplenty at Heritage Farm, Seed Savers Exchange’s headquarters in northeast Iowa. 

But, as an inquisitive group of Luther College students recently discovered, the farm’s 890 acres also contains a forest that myriad rare flora and fauna call home. “Heritage Farm has a patch of forest that appears never to have been cleared or heavily grazed,” notes Beth Lynch, Luther associate professor of biology and Seed Savers Exchange board member. “As a result, it has relatively high plant diversity, including several species, like leatherwood, that are uncommon in Iowa.” 

Leatherwood—scientific name Dirca palustris—is a small, deciduous shrub that grows throughout the eastern United States and Canada. In northeast Iowa, however, it’s generally restricted to high-quality sites like Heritage Farm, which, according to Lynch, has one of the largest populations of the shrub in the state. And because there’s so much leatherwood on the farm, there are also many Leucanthiza dircella, tiny moths that have such an affinity for the shrub that they lay their eggs inside its leaves in early summer.  

Eventually, these eggs hatch into larvae that spend the summer living in the leaf, creating blotches that reveal where they have eaten it out. (This behavior has earned the larvae the name “leaf miners.”) The moth’s basic biology remains a mystery, however, and thus provided plenty of research fodder this fall for students in Lynch’s Biology 365 class, who sought answers to carefully crafted questions.

Luther College students Sau Khadka and Bishal Parajuli collect data in a forested part of Heritage Farm. Photo by Beth Lynch.

Among the questions the students asked: How do the moths find the plants and then choose where to lay their eggs? How many generations do the moths go through in a year? And when the larvae pupate, where they pupate? (A pupa is the life stage of some insects undergoing transformation between immature and mature stages.) 

After analyzing data collected in the farm’s forest during the first and third weeks of the semester, the class determined that almost all of the larvae pupated between September 5 and 19 and that the pupae do not remain in the leaves but, instead, overwinter on the soil surface. They also found no evidence that the moths have more than one generation per year, even though, says Lynch, research had suggested otherwise in Ohio and southern Michigan (but not in northern Michigan). Students will present their research at a symposium to be held on campus in December.

A clipboard holds research data collected by students in the Luther College Biology 365 class. Photo by Beth Lynch.

“I liked that we were able to focus on one plant-insect system about which so little basic biology is known,” says Lynch. “I also liked that students saw firsthand how valuable some Iowa forests are because they have species found nowhere else in the region—Seed Savers Exchange, for one, is home to some very rare plant species and the equally rare insects that depend on them.”

Student or not, you can enjoy the forest beauty of Seed Savers Exchange’s Heritage Farm on miles of hiking trails open year-round to the public.