The Boulder Chapter welcomes those in Boulder County and surrounding areas. 

The Boulder Chapter embraces diversity in not only traditional matters of civil rights but also diversity in botanical interests and expertise. Our members range from experienced professional botanists with broad ecological skills to amateurs just learning about our wonderful native flora. By offering classes, workshops, meetings, and field trips to all members, we strive to share our love of native plants and encourage all members to improve their knowledge and skills.

We hold winter meetings from October-April on the first Wednesday of each month from 7-8:30 pm. These meetings are currently virtual on the GoToMeeting platform. When meetings are in person, location will be announced in the chapter newsletter. There are field trips that take place in the summer, typically April-August. Event information can be found in the chapter newsletter and on the CoNPS event calendar. Please email if you have questions. 

The Denver Chapter webpage has good resources on plant identification.

A Cautinary Tale About Native and Non-Native Thistles

The widely diverse topography in Boulder County -- from plains to alpine tundra - creates a unique opportunity for plants - approximately 1,500 vascular plants occur within the 750 square miles of Boulder County, which represent nearly half of all the plant species found in Colorado.*  The Continental Divide (the county’s western boundary) reaches its easternmost approach in North America, and its steepest gradient and shortest distance between the high peaks and plains. The Flatirons of the City of Boulder reach 8,000 feet, forming a sharply tilted wall where mesic conditions allow for a varied floristic community.

The Central Great Plains and the Southern Rocky Mountain ecoregions meet in Boulder County.  The convergence of forested foothills and prairie grasslands provides particularly diverse habitats:  Bell’s twinpod (Physaria bellii), a rare plant found only in Boulder and Larimer Counties, grows here on shale barrens in grasslands.  Another rare species, Prairie Violet (Viola pedatifida) is found in our county's grasslands and open ponderosa pine forests. Also in the foothills, on rocky or sandy soils, is the rare dwarf leadplant (Amorpha nana). The county’s high-quality wetlands and riparian areas are another prime location for native plants, including the federally threatened Ute ladies’-tresses orchid (Spiranthes diluvialis). Coupling with the incredible floral richness is the diversity of pollinators such as bees and butterflies. 

* Webpage content contains excerpts from Weber, William A., 1995. Checklist of Vascular Plants of Boulder County, Colorado. Natural History Inventory of Colorado, No. 16. University of Colorado Museum, Boulder, Colorado.

Prairie Violet (Viola pedatifida)
Photo by Anna Theodorakos.

Ute ladies’-tresses orchid
(Spiranthes diluvialis)
Photo by Anna Theodorakos.
Trail to Isabel Lake, Indian Peaks Wilderness, Arapaho National Forest. Photo by Richard Kiefer
Yellowspine Thistle(Cirsium ochrocentrum)
Photo by Anna Theodorakos.