University of Maryland Medical Center - Provides an overview of the plant alongside its available forms and how to take it. Includes precautions and supporting research. Diagnose Me - Echinacea - Herb's overview and why is it recommended. Wikipedia: Echinacea - Species, history, and side effects. NCCIH - Echinacea - Displays a short introduction along with possible side effects. Key references available. Mayo Clinic: Echinacea - Offers comprehensive information including evidence, dosing, and selected references. BBC - Does echinacea prevent colds? - Article focused on whether or not this herb reduces the risk of contracting a cold. Herbwisdom.com - Echinacea - Benefits, notes, and side effects. MSKCC - Echinacea - Includes information on uses, constituents, and warnings. References Included. NRCS - Echinacea - Presents an interactive map indicating where the herb grows in the US. Related links available. Clemson Extension HGIC - Echinacea's culture, issues, and species. Herbazest - Echinacea - Presents an overview of the plant's compounds, forms of consumption, and growing option alongside an in-depth guide of its medicinal properties. NewCROP - Genus Echinacea - Provides a summary of the genus by species and concluding remarks. University of Wisconsin - Echinacea purpurea - Thorough section covering the herb's classification, habitat, and interactions.