FBEFACE. XI 



lopeg, viz. with both calyx and corolla, and in which the corolla consi»ts of 

 separate petals (the Polypetaloits divifdon) ; beginning this series with those 

 orders in which the several organs of the flower are most distinct and 

 separate Qiypogynous), and proceeding to those which have the parts most 

 combined among themselves and consolidated with each other (perigynous 

 and epigynous) ; then follow those with the petals combined into a mono- 

 petalous corolla (the Monopetalous division) ; and, finally, those destitute of 

 a corolla or destitute of all floral envelopes (the Apetcdous division). The 

 class of Monocoiyledonous or Endogenous Plants opens with orders exhibit- 

 ing one form of simplified flowers, passes to those with the organs most 

 combined and consolidated, then to those most perfect and less combined, 

 and closes with other simplified and reduced forms. The present problem 

 in Botany is to group the numerous Natural Orders in each class into nat- 

 ural alliances. But this has not yet been done in such a manner as to be 

 available to the ordinary student. 



I do not here attempt, therefore, to group the orders naturally, but let 

 them follow one another in what seems to be on the whole the most natu- 

 ral and practically convenient sequence. And, by means of an Analytical 

 Artificial Key to the Natural Orders* (p. xvii.), I enable the student very 

 readily to refer any of our plants to its proper Family. This Key is 

 entirely remodelled in the present edition, is founded on characters of 

 easy observation, and is so arranged as to provide for aU the exceptional 

 instances and variant cases I could think of I shall be disappointed if the 

 attentive student is not able by it to refer to its proper order any to him 

 unknown plant of the Northern States of which he has flowering speci- 

 mens. Referring to the Order indicated, the student will find its dis- 

 tinctive points, which he has chiefly to consider, brought together and 

 printed in italics in the first sentence of the description. 



Then, to abridge the labor of further analysis as much as possible, I 

 have given a synopsis of the genera under each order, whenever it com- 

 prises three or more of them, enumerating some of their leading characters, 

 and grouping them under their respective tribes, suborders, &c., as the 

 case may be. I have also taken pains to dispose the species of every ex- 

 tensive genus under sections (§) or subgenera (§ with a name in capitals), 

 subsections ( * ), and subordinate divisioiSs (-i-, ++, &c.) ; and whenever 

 there are two or more species under a division, I have italicized some of 

 the principal distinctions (after the manner of Koch's Flora Germanicd), 

 so that they may at once catch the student's eye. 



To aid in the pronunciation of the generic and specific names, &c., I 



* No LiiiDSean Artificial Arrangement is here given, experience having shown that, as a Key 

 to the Natural Orders or to the genera, it offers no clear advantage on the score of facility over 

 a well-devised Analytical Key ; which the learner will find equally certain, and much mOTB 

 satisfactory in its results. 



