For the student in the northern United States, Gray's Manual and 

 Wood's Class Book give most of the Filices, Equisetaceae, Lycopodiaceae, 

 Isoetaceae, Marsiliaceae, and Salviniaceae. The Musei and Hepaticae are 

 described by Sullivant, whose work has been incorporated with Gray's 

 Manual. Harvey's Nereis Boreali- Americana, and Wood's " Contribu- 

 tion to the History of the Fresh Water Algae of North America, Wash- 

 ington, 1872," must be referred to for our Algae; and for the Diatoma- 

 ceae we must go to the work of Kabenhorst, which is written in Latin 

 and does not apply specially to our country. Tuckerman gives only 

 generic descriptions of the Lichens. Cook's Handbook of British Fungi 

 includes a large number of American species. 



Of late years a multitude of zealous workers have cleared up much of 

 the mystery which enshrouded the flowerless plants in the time of Lin- 

 naeus, and the time is not far distant when it will be no longer correct to 

 speak of the phanerogamic and cryptogamic, but the distinction will be 

 between seed plants and spore plants. 



Before proceeding with the artificial, analytical key we may give a 

 concise, general view of the vegetable kingdom thus: 



I. FLOWERING PLANTS. 



A. EXOGENS. 



A. Perianth of two whorls or more. 

 1. Corollifloral. 



a. Stamens perigynous. 



b. Stamens hypogynous. 

 2. Calycifloral. 8. Thalainiflurnl. 



a. Polypetalous. a. Stamens few. 



b. Monopetalous. b. Stamens many. 



B. Perianth of one whorl or none. 

 1. Angiospermous, as Salicaceae. 

 '2. Gymnospermous, as Coniferae, Cycadaccac. 



B. ENDOGENS. 



a. Petaloideous, as Liliaceae. 



b. Spadiceous, as Palmae, Araci-;r. 



c. Glumaceous; Cyperaceae, Gramineae. 



