[1. McGregor RL. The taxonomy of the genus Echinacea (Compositae). The University of Kansas Science Bulletin 1968; 48:113-42.]Search in Google Scholar
[2. McKeown KA. A review of taxonomy of the genus Echinacea. In: Janick J (ed.). Perspectives on New Crops and New Uses. Purdue University 1999:482-90.]Search in Google Scholar
[3. Bauer R, Wagner H. Echinacea species as potential immunostimulatory drugs. In: Wagner H, Farnsworth NR (eds). Economic and medicinal plant research. Vol 5. Academic Press 1991:253-321.]Search in Google Scholar
[4. Barrett B. Medicinal properties of Echinacea: a critical review. Phytomed 2003; 10:66-86.10.1078/094471103321648692]Search in Google Scholar
[5. Bauer R, Foster S. Analysis of alkamides and caffeic acids derivatives from Echinacea simulata and E. paradoxa roots. Planta Med 1991; 57:447-9.10.1055/s-2006-960147]Search in Google Scholar
[6. Bergeron C, Gafner S, Batcha LL, Angerhofer K. Stabilization of caffeic acid derivatives in Echinacea purpurea L. glycerin extract. J Agric Food Chem 2002; 5:3967-70.10.1021/jf011582m]Search in Google Scholar
[7. Qu L, Wang X, Yang J, Hood E, Scalzo RE. Ethephon promotes germination of Echinacea angustifolia and E. palida in darkness. HortScience 2004; 39:1101-03.10.21273/HORTSCI.39.5.1101]Search in Google Scholar
[8. Shalaby AS, Agina EA, El-Gengaihi SE, El-Khayat AS, Hindawy SF. Response of Echinacea to some agricultural practices. J Herbs Spices Med Plants 1999; 4:59-67.10.1300/J044v04n04_07]Search in Google Scholar
[9. Bishnoi UR, Willis JE, Rao Mentreddy S. Methods to improve seed germination of purple coneflower (Echinacea purpurea (L.) Moench). Agric Biol J N Amer 2010; 1:185-88.10.5251/abjna.2010.1.3.185.188]Search in Google Scholar
[10. Fariman KZ, Azizi M, Noori S. Seed germination and dormancy breaking techniques for Echinacea purpurea. J Biol Environ 2011; 5:7-10.]Search in Google Scholar
[11. Rajabian T, Saboura A, Hasani B, Falah Hosseini H. Effects of GA3 and chilling on seed germination of Ferula assa-foetida, as a medicinal plant. Iranian J Med Aroma Plant 2007; 23:391-404.]Search in Google Scholar
[12. ISTA. International rules for seed testing. Seed Sci Tech 1993; 21: Supplement]Search in Google Scholar
[13. Ellis RH, Roberts EH. The quantification of ageing and survival in orthodox seeds. Seed Sci Tech 1981; 9:373-409.]Search in Google Scholar
[14. Chuanren D, Bochu W, Wanquian L, Jing C, Huan A. Effect of chemical and physical factors to improve the germination rate of Echinacea angustifolia seeds. Colloids and Surf B: Biointerfaces 2004; 37:101-5.10.1016/j.colsurfb.2004.07.003]Search in Google Scholar
[15. Nadjaf M, Rastgoo M. Seed germination and dormancy breaking technique for Ferula gummosa and Teucrium polium. J Arid Environ 2006; 55:29-42.10.1016/j.jaridenv.2005.06.009]Search in Google Scholar
[16. Macchia M, Angelini LG, Ceccarini L. Methods to overcome seed dormancy in Echinacea angustifolia DC. Sci Hort 2001; 89:317-24.10.1016/S0304-4238(00)00268-5]Search in Google Scholar
[17. Wartidiningsih N, Geneve RL, Kester ST. Osmotic priming or chilling stratification improves seed germination of purple coneflower. Hortscience 1994; 29:1445-8.10.21273/HORTSCI.29.12.1445]Search in Google Scholar
[18. Baskine CC, Baskin JM, Hoffman GR. Seed dormancy in the prairie forbs Echinacea angustifolia var. angustifolia (Asteraceae): after-ripening pattern during cold stratification. Int J Plant Sci 1992; 153:239-43.10.1086/297027]Search in Google Scholar
[19. Romero F, Delate K, Hannapel D. The effect of seed source, light during germination and cold moist stratification on seed germination in three species of Echinacea for organic production. HortScience 2000; 40:1751-4.10.21273/HORTSCI.40.6.1751]Search in Google Scholar
[20. Yamauchi Y, Ogawa M, Yamauchi S. Activation of gibberellins biosynthesis and response pathways by low temperature during imbibitions of Arabidopsis thaliana seeds. Plant Cell 2004; 16:367-78.10.1105/tpc.01814334191014729916]Search in Google Scholar
[21. Tipirdamaz R, Gomurgen N. The effects of temperature and gibberellic acid on germination of Eranthis hyemalis seeds. J Bot 2000; 24:143-5.]Search in Google Scholar
[22. El-Darier SM, Yossef RS. Effect of soil type, salinity and alleochemical on germination and seedling growth of medical plant Lepidium sativum L. Ann App Biol 2000; 136:273-9.10.1111/j.1744-7348.2000.tb00035.x]Search in Google Scholar
[23. Delesalle VA, Blum S. Variation in germination and survival among families of Sagittaria latifolia in response to salinity and temperature. Int J Plant Sci 1994; 155:187-95.10.1086/297158]Search in Google Scholar