208 LETTER XVII. 



When we were talking of Umbelliferous plants I 

 cautioned you against committing the error of sup- 

 posing that all plants with their flowers in umbels 

 belonged to that natural order. In like manner I 

 must now explain to you that although the arrange- 

 ment of florets m heads is universal in Composite 

 flowers, yet that there are many plants in the world 

 whose florets are placed in the same manner, but 

 which do not belong to this tribe. For instance, 

 Eryngo, which is an Umbelliferous plant, has its 

 flowers in heads, so has Sanicle, another genus of the 

 same order ; and Teasel (Dipsacus) and Scabious 

 (Scabiosa) are so extremely like Composite flowers 

 in appearance, that you would never suspect them of 

 being strangers of another family, if you were not 

 apprized that no plants belong to the tribe of Com- 

 posite flowers, which have not their anthers united 

 into a cylinder. This it is which, taken with the dis- 

 position of the florets in heads, alone gives a positive 

 character to the plants I have been speaking of. 

 This remembered, you are mistress of the key to six 

 or seven thousand species. 



A few words upon the plant called Ribgrass, to which 

 I have already alluded, and I pass at once to my promis- 

 ed analysis of the Monopetalous Dicotyledonous orders. 



Ribgrass (Plantago) is a weed common at the foot 

 of walls, by the side of pathways, and in moist places 

 generally. It derives its name from its leaves having 

 remarkably strong ribs passing from the bottom to 

 the top : it has no apparent stem, but the leaves lie 

 flat on the ground. The flowers (Plate XVII. 2. fig. 1 .) 



