CHAPTER VII

PHYLOGENY

I. GENERAL STATEMENT

A. ORIGIN OF LICHENS 272

B. ALGAL ANCESTORS 273

C. FUNGAL ANCESTORS 273 _a._ Basidiolichens _b._ Ascolichens

II. THE REPRODUCTIVE ORGANS

A. THEORIES OF DESCENT IN ASCOLICHENS 273

B. RELATION OF LICHENS TO FUNGI 275 _a._ Pyrenocarpineae _b._ Coniocarpineae _c._ Graphidineae _d._ Cyclocarpineae

III. THE THALLUS

A. GENERAL OUTLINE OF DEVELOPMENT OF THALLUS 281 _a._ Preliminary considerations _b._ Course of evolution in Hymenolichens _c._ Course of evolution in Ascolichens

B. COMPARATIVE ANTIQUITY OF ALGAL SYMBIONTS 282

C. EVOLUTION OF PHYCOLICHENS 283 _a._ Gloeolichens _b._ Ephebaceae and Collemaceae _c._ Pyrenidiaceae _d._ Heppiaceae and Pannariaceae _e._ Peltigeraceae and Stictaceae

D. EVOLUTION OF ARCHILICHENS 287 _a._ Thallus of Pyrenocarpineae _b._ Thallus of Coniocarpineae _c._ Thallus of Graphidineae _d._ Thallus of Cyclocarpineae _AA._ LECIDEALES _aa._ Coenogoniaceae _bb._ Lecideaceae and Gyrophoraceae _cc._ Cladoniaceae 1. Origin of Cladonia 2. Evolution of the primary thallus 3. Evolution of the secondary thallus 4. Course of podetial development 5. Variation in Cladonia 6. Causes of variation 7. Podetial development and spore-dissemination 8. Pilophorus, Stereocaulon and Argopsis _BB._ LECANORALES _aa._ Course of Development _bb._ Lecanoraceae _cc._ Parmeliaceae _dd._ Usneaceae _ee._ Physciaceae