5 TPIE BOTAXISTS OF PHILADELPHIA. 



Pursh published in London, in 1814, his vaUial)le and com- 

 prehensive work, Flora Americae Septentrionalis."^' 



Arranged according to the Linn^an s>^stem there ap- 

 peared in 1818, in two volumes, Dr. William P. C. Barton'sf 

 Compendium Flone Philadelphica?, a hastily digested, but 

 thoroughly useful liand-book of tlie region. 



Botanical works and papers began now to multiply, 

 and the third period of Philadelphia botany was fairly 

 entered upon with the publication in 1818 of Nuttall's 

 " Genera of North American Plants,'" at Philadelphia. | 



(3) Development of the Natural System under the in- 

 fluence of the doctrine of the constancy of species. A 

 new direction to the study of systematic botany, and mor- 

 phology was given in France, where the sexual system had 

 never met with great accei:)tance. Bernard de Jussieu and 

 his nephew, Antoine Laurent de Jussieu, taking up Lin- 

 naeus' profounder and properly scientific efforts, made the 

 working out of the natural system, in Linnaeus' own oi)inion 

 the highest aim of botany, the task of their lives. The 

 key was given by the study of the order Ranunculaceffi in 

 the Jardin des Plantes. In 1789 Jussieu's System appeared. 

 It was not until 1815 that the natural system of Jussieu 

 was received by the botanists of Philadelphia. In that 

 year Abbe Correa published for the use of his class in 

 Philadelphia a reduction of the genera of Muhlenberg's 

 Catalogue according to the system of Jussieu. This was 



*1814. Pl'RSH — Flora Americce septentrionalis, or a systematic arrangement 

 and description of the^tlants of North America. London, II vols. 



flSlS. W. P. C. Barton— CotJipendmm Florce Philadelphica; , coyiiaining a 

 description of the indigenous and naturalized jilants found ivithin a circuit often 

 miles around Philadelphia. Thiladelphia, II vols. 8. I. Preface 251 pp. II. 234 pp. 

 cum indices. 



JISIS. NuTTALL— T/i« Genera of North American Plants, and a catalogue of 

 the species of the year 1S17. Philadelphia, II vols. 



