NRCS – Texas 1 

Technical Note No: TX-PM-10-5

United States Department of Agriculture

Natural Resources Conservation Service

Technical Note No: TX-PM-10-5

August 2010

What Are Plant Ecotypes?

Plant Materials Technical Note

Variation in early greenup of switchgrass collections in a common garden plot, Shelly Maher, E. “Kika” de la Garza PMC

Range scientists and agronomists have shown that individual species having a large 

geographical distribution vary considerably in such characteristics as plant height, growth 

habits, maturation dates, leaf appearance, and reproductive habits. These characteristics are 

not distributed randomly throughout the range of the species but are clustered into ecological 

regions (ecoregions) or seed transfer zones. Plants within these ecological regions are known as 

ecotypes. 

Ecotypes were first recognized by scientists as far back as the 1920’s. Grass ecotypes 

assembled in common garden studies revealed that northern ecotypes of sideoats grama

flower earlier than more southern ecotypes, resulting in shorter plants. Ecotypes of little 

bluestem originating from either sandy or clay soils did not do well when placed on soils of the 

opposite texture. More recently Dr. Danny Gustafson found that genetic, morphological and 

phenological differences existed between ecoregional sources of big bluestem, Indiangrass and 

purple prairie clover. 

Locally adapted plant materials are widely recommended because of their increased chances of 

establishment success and genetic compatibility with surrounding populations. However, it is 

important to consider the isolation and thus the potential genetic inbreeding of limiting oneself 

solely to localized remnant populations. Frequently people try to simplify what an ecotype is by 

stating that it is a plant that is within 100-200 miles of its center of origin. But this 

oversimplifies, and fails to take into account that ecotypes are based on such factors as soil 

type, elevation, exposure, life form, breeding system, and seed dispersal mechanisms. 

In order to avoid restored populations with low genetic diversity and limited potential to evolve 

to a climatically changing environment, ecotypes have been developed from ecoregions or seed 

transfer zones. When developed by relating patterns of genetic variation among populations to 
NRCS – Texas 2 

Technical Note No: TX-PM-10-5

environmental factors one can achieve a balance between minimizing unintended 

consequences of moving plant materials and maximizing seed production efficiency and genetic 

diversity. 

Common gardens have been used to examine genetic differences between populations and to 

identify environmental factors that may cause local adaptation. In a common garden study, all 

the plants are grown in the same plot under the same environmental conditions. Thus, 

differences expressed in the plants morphological and phenological traits are due to their 

underlying genetics not due to the environment. In a study conducted in Oregon, “Can an 

Ecoregion Serve as a Seed Transfer Zone?” Evidence from a Common Garden Study with Five 

Native Species (Miller et al., 2010) four of the five species evaluated had compatible 

populations for combining under a single ecoregion. Their conclusion from this study was 

“Ecoregions may be appropriate for some species as seed transfer zones in the absence of 

genetic data to improve the efficiency, economy, and genetic diversity of seeds produced for 

restoration. This may be especially valid in regions with little variation in topography or 

climate. At the same time, seed transfer zones of this scale may guard against outbreeding 

depression and use of poorly adapted genotypes.” It is with this carefully managed ecotype 

approach combined with selective genetic screening that South Texas Natives (STN) and the E. 

“Kika” de la Garza Plant Materials Center hope will improve their efforts to release commercial 

seed that is adapted, diverse and appropriate for the landowners of South Texas. 

References:

Gustafson, D. J., D. J. Gibson, and D. L. Nickrent. 2005. Using local seed in prairie restoration—

data support the paradigm. Native Plants Journal 6:25–28.

Miller, S. A. et al. 2010. Can an Ecoregion Serve as a Seed Transfer Zone? Evidence from a 

Common Garden Study with Five Native Species. Restoration Ecology, no. doi: 10.1111/j.1526-

100X.2010.00702.x

For additional information please contact:

E. “Kika” de la Garza Plant Materials Center

3409 N FM 1355

Kingsville, TX 78363-2704

361-595-1313

www.tx.nrcs.usda.gov/technical/pmc/kingsville.html

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