CONTENTS. 



PAOB 



Introduction 3 



Scope and duty of taxonomy 3 



Scope 3 



Relation to ecology and experimental evolution. . 3 



Duty 4 



Scientific basis of taxonomy 4 



Classification and relationship 4 



Evolution and phylogeny 5 



Synthesis and analysis 5 



The genus concept 6 



Nature of the genus 6 



Genus and section 6 



Generic segregation 7 



Failures of segregation 7 



Proper treatment of genera 8 



The species concept 9 



Nature of the species 9 



Definition of species 9 



Constancy 10 



Distinctness 10 



Evolutionary definition 11 



Segregation of species 11 



Failures of specific segregation 12 



Scientific basis of species 14 



Nomenclature 16 



Purpose and value 16 



Future r61e 16 



Essentials of stability 17 



Practical nomenclature 17 



A binomial system of common names 19 



Methods and results in evolutionary taxonomy .... 19 



Methods 19 



Statistics 19 



Experiment 20 



Method of experiment 21 



Objectives 22 



Variads 23 



Methods of treatment 23 



General plan 23 



Field work 24 



Results of statistical studies and experiments. ... 25 



Illustrations 26 



Phylogenetic charts 27 



Citation of authors, synonyms, and specimens. . . 27 



Herbaria studied and acknowledgments 28 



References 30 



Genus Artemisia 31 



Relationships and generic limits 31 



Origin and development of the sections 34 



Criteria for recognition of species and subspecies. . . 37 



Achene 37 



Style-branches 38 



Corolla 38 



Number and reduction of flowers in the head ... 39 



Involucre 40 



Inflorescence 40 



Leaves 41 



Stem and bark 42 



Roots 43 



Pubescence 43 



Resins, oils, and odors 43 



Habit 43 



PAGE 



Genus Artcmi.sia — Continued. 



Relative plasticity of the species 44 



Generic diagnosis 45 



Key to sections of Artemisia 46 



Key to North American species of Artemisia 46 



Artificial key to North American species of 



Artemisia 47 



Section I. Abrotanum 49 



Phylogeny of the species 49 



1. Artemisia abrotanum 49 



Description 49 



Distribution 51 



Minor variations 61 



Relationships 51 



Ecology and uses 51 



2. Artemisia pontica 62 



3. Artemisia californica 53 



4. Artemisia macrobotrys 66 



5. Artemisia norvegica 67 



6. Artemisia senjavinensis 65 



7. Artemisia parryi 66 



8. Artemisia stelleriana 67 



9. Artemisia alaskana 68 



10. Artemisia franserioides 69 



11. Artemisia vulgaris 71 



12. Artemisia biennis 101 



13. Artemisia annua 102 



14. Artemisia klotzschiana 103 



15. Artemisia bigelovi 104 



Section II. Absinthium 106 



Phylogeny of the species 106 



16. Artemisia absinthium 106 



17. Artemisia frigida 108 



18. Artemisia scopulorum 110 



19. Artemisia pattersoni 112 



Section III. Dracunculus 114 



Phylogeny of the species 114 



20. Artemisia dracunculus 115 



21. Artemisia campestris 120 



22. Artemisia filifolia 130 



23. Artemisia pedatifida 131 



24. Artemisia .spinescens 132 



Section IV. Seriphidium 134 



Phylogeny of the species 134 



25. Artemisia tridentata 135 



26. Artfemisia cana 150 



27. Artemisia rigida 153 



28. Artemisia pygmaea 154 



29. Artemisia palmeri 155 



Genus Chrysothamnus 157 



History, limits, and relationships 157 



Division into sections 160 



Origin and development of sections 161 



Criteria for recognition of species and subspecies. . . 164 



Achene 164 



Pappus 164 



Style-branches 164 



Stamens 165 



Corolla 165 



Number of flowers in the head 167 



Involucre 167 



Inflorescence 169 



