398 SrSTEMATlC BOTANY, OR 



semblc one another in the structure and general characters of 

 their organs of reproduction. It does not necessarily happen 

 that a genus should contain a number of species, for, if a 

 single one presents peculiarities of a marked kind, it may of 

 itself constitute a genus. 



It frequently happens that, two or more species of a genus 

 have a more striking resemblance to each other in certain im- 

 portant characters than to other species of the same genus; in 

 which case they are grouped together under the name of a sub- 

 genus. 



3. Okders or Families. — If we regard collections of genera 

 in the same point of view as we have just done those of species, — 

 that is, as to their resemblance or family likeness, — we shall find 

 that some of them also resemble one another more than they do 

 others. Thus Mustards, Turnips, Radishes, and Cabbages, have 

 a strong common resemblance, while they are unlike Straw- 

 berries and Brambles; and even less so to Hazels, Oaks, and 

 Beeches; and still more unlike Larches, Pines, Firs, and 

 Cedars. Proceeding in this way throughout the vegetable 

 kingdom, we collect together allied genera, and form them into 

 groups of a higher order called Orders or Families; hence, 

 while genera are collections of related species, orders are col- 

 lections of allied genera. Thus Mustards, Turnips, Radishes, 

 Cabbages, all belong to different genera, but they all agree in 

 their general structure, and are hence included in the order 

 Cruciferai; while Strawberries, Brambles, Cinquefoils, Roses, 

 Apples, Plums, Almonds, are all different genera, but from the 

 general resemblance they bear to one another in their structure, 

 they are placed in one order, called Rosace*. Again, Oaks, 

 Beeches, and Hazels, are different genera, but they belong to 

 one order; also the Larches, Pines, and Cypresses, are difl^crent 

 genera, but they all have a fruit called a cone, and are hence 

 placed in one order, the Coniferaj. 



We find also that certain genera of an order, like certain 

 species of a genus, have a more striking resemblance to one 

 another tlian to other genera of the same order; hence such are 

 grouped together into what are called Sub-orders. Thus the 

 Chicory, Dandelion, Sowthistle, Lettuce, Thistle, Burdock, 

 Chamomile, Ox-eye, all belong to the same order, but there 

 is a greater resemblance in the Chicory, Dandelion, Sowthistle, 

 and Lettuce, to one another, than to the remaining genera; 

 while of those again the Thistle and Burdock arc more nearly 

 related to each other than they are to the Ox-eye and Chamo- 

 mile. Hence, while all the above genera belong to the order 

 Compositie, they are at the same time placed in three tlifforcnt 

 sub-orders. Thus the sub-order Cichoraceje includes the 

 Chicory, Dandelion, Sowthistle, and Lettuce; the sub-order 

 Cynarocephala; includes the Thistle and the Burdock; and that 



