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About Native Iowa Woodland Understory Restoration

Guide Content

Our goal for this guide is to provide seed collection information, and guidance on whether it is best to introduce a species by seed or transplants, focusing on shade tolerant herbaceous (non woody) species that occur in closed canopy forests in central Iowa (but also applicable to much of the state). For the most part the species here are not included in prairie propagation references. The database includes:

  1. Flowering time for central Iowa
  2. Signs of fruit maturation
  3. Fruit maturation dates for central Iowa
  4. Seed cleaning and storage recommendations
  5. Restoration Potential Rating

NOTE: For species that do not tolerate dry storage, seeds must be sowed directly outside after harvest, or stored in cold moist sphagnum until ready to sow. Most woodland species germinate better after a period of cold moist stratification, for example by sowing in November or December before snow fall.

Most of the species included here would benefit from further observation and experimentation. If you have experience collecting, storing, and/or propagating these species, please consider contributing to this database by submitting information to Cathy McMullen (

The original information in this database was compiled between 1998 and 2010 by Cathy Mabry McMullen, adjunct associate professor at Iowa State University and Larissa Mottl, biological field station manager at Grinnell College. The database is maintained by Cathy McMullen and will continue to be updated as we learn about the propagation and restoration potential of more species. We invite users to evaluate the information and provide feedback and new information from users will help expand and improve the database. Please send any additional information on plants, and any typos or corrections to Cathy McMullen (

Iowa Woodlands and Urban Landscapes

Pammel Woods, Iowa State University      Oak/Hickory Forest

Restoration Needed 

Many Iowa woodlands no longer contain the diversity of herbaceous and woody species that once provided soil stabilization, nutrient retention and recycling, soil organic matter, and wildlife food and habitat. Woodlands in private ownership that have been used as pasture for many decades suffer from soil compaction, soil loss, and a ground cover composed of a distinct suite of non-native and native generalist species. Other woodlands that have been protected on private land and in state parks, preserves, and wildlife areas, suffer from severe herbivory by dense deer populations and invasions by exotic trees and shrubs (buckthorn, bush honeysuckles, multiflora rose, and Siberian elm), exotic herbaceous species (like garlic mustard). The pre-1900 logging history in Iowa followed by over a century of fire suppression, cattle grazing, and numerous introductions of invasives species have significantly altered Iowa's woodlands and greatly reduced their capacities to function within the landscape.

Due to extreme habitat fragmentation, limited dispersal abilities, and complicated germination requirements, many woodland herbaceous species do not re-establish in woodlands when major disturbances are reduced or cease. Life history characters of many woodland species make restoration by seed, a common strategy for prairie and wetland restorations, more expensive, slow, and infeasible because (1) many species produce few seeds, especially less common species, (2) the seed often has exacting germination requirements and low viability, and (3) some species may take many years to reach reproductive maturity, thereby lengthening the time required for a species to spread and increase its population at a site.

In addition, forest herbaceous species can give urban homeowners an alternative to lawns, particularly in full and partial shade. Use proven performers (explained in the Restoration Techniques tab) as a guide to what plants to start with. For example, see the Ames Insect Initiative, a program to encourage pollinators through replacing lawn with plants like clover and native species.

The information in this guide can be used to determine which species can be sown directly at a restoration site and which species are best introduced as transplants, either purchased from a native plant nursery (midwestern nurseries are listed under resources).

Camp Dodge Sign Acknowledgements

  • Financial support was provided by Camp Dodge, Iowa Army National Guard Military Reservation, Johnston, IA; McIntire-Stennis funds, Department of Natural Resource Ecology and Management, Iowa State University, Ames, IA, and Grinnell College, Grinnell, IA