OF ARTS AND SCIENCES. 8V 



be limited only by taking into account a combination of characters, and 

 insisting here upon one, there upon another. The general differences 

 between it and Aster are found, — 1. in the simpler involucre, of equal 

 neither foliaceous nor appendiculate narrow bracts ; 2. in the very 

 numerous and narrow rays of the typical species ; 3. in the very short, 

 broad, and obtuse style-appendages ; 4. simpler stems, naked above or 

 with few more pedunculate heads ; 5. less copious and more fragile 

 pappus ; 6. smaller achenia ; their nervation is of little importance, 

 but mostly there are only the marginal nerves. We adopt the genus 

 with the extension which Bentham and Hooker, following our lead, 

 now give to it. The various nominal genera which have been predi- 

 cated on the pappus and the number of ray-flowers are nearly una- 

 vailable for good subgenera. The following arrangement, in which 

 the needs of the student are much considered, commences with some 

 of the most Asteroid forms, and ends with the species which merge 

 in Conyza. The three primary sections here adopted are not very 

 strictly characterizable ; the two larger are connected by a small inter- 

 mediate group. 



§ 1. EuERiGERON. Flores foeminei omnibus ligulatse ligulis elon 

 gatis, in perpaucis nuUi. 



Series 1. Perennes. 



1. Species Am.-Bor.-Orientales, glabratse, parviflorae ; ligulis 20-25 

 plerumque albis; acheniis 2-4-nervatis ; pappo simplicissimo. — 

 § Erigeridium, Torr. & Gray. 



E. HYSSOPiFOLius, Michx. Fl. ii. 123. Aster graminifolius, Pursh. 

 Fl. ii. 545. — Northern New England to Hudson's Bay, &c., west to 

 shore of Lake Superior. 



E. NUDiCAULis, Michx. 1. c. E. vernus, Torr. & Gray, Fl. ii. 176. 

 E. integrifolius, Bertol. Misc. vi. t. 3, non Bigel. Aster vernus, L. 

 Stenactis verna, Nees, DC. — Pine barrens near the coast, Virginia 

 to Louisiana. 



2. Species Californicae, etc., ligulis nullis ; pappo simplici. 



* Subcaulescens, pedunculis scapiformibus monocephalis. 



E. Bloomeri, Gray, Proc. Am. Acad. vi. 40. — Sierra Nevada, 

 California to W. Oregon. 



* * Foliosissimae, humiles ; capitulis saepius solitariis. 



E. SUPPLEX, Gray, Proc. Am. Acad. vii. 353. — N. E. California, 

 Bolander, &c. 



