natural Family of Flants called Composit<e. ] 13 



anil besides these, one or two minute processes are generally ob- 

 servable. Stigmata revolute*. 



In the 12th edition of Systema Naturae, Linneus added to his 

 genus C'«/efl a. fourth species, namely Galea scoparia; for what rea- 

 son it would be difficult to discover, as it does not resemble, either 



* In the remarkable character of its re-curved florets, as well as in sortie other respects 

 this species of Salmea agrees with SpUantlius arboreus of George Forster (in Commentat. 

 Gotting. ix. p. 66.), of which he originally formed his genus Laxmannia ; from a very er- 

 roneous view of its structure, however, having described the Nectarium or glandula epigyna 

 as a " germen superum ;" the real, though imperfect, germen with its two aristae as a 

 " perianthium bidentatum," and consequently referring the genus to Polygamia segregata. 



When he afterwards corrected tliese ervors and reduced Laxmannia to Spilanthus, he 

 did not discover that he had only the imperfect hermaphrodite or male plant before him. 



That Spilanlhus nrlioreiis is really dioecious, I have ascertained from the examination of 

 numerous specimens collected by Sir Joseph Banks in the Island of St. Helena, where it 

 forms a small tree called by the inhabitants White-wood. It is Bidens ariorea and per- 

 haps also Spllatilhus tetrandrus of Dr. Roxburgh's List of Plants appended to General Beat- 

 son's Tracts on St. Helena ; the former being probably the female, the latter as tarved 

 variety of the male plant. 



In re-establishing Spilanthus arboreus as a genus, sufficiently distinct from Bidens, Spi- 

 lanthus, and Satmea, it will not, I conclude, be considered expedient to recur to Forster's 

 name Laxmannia, which as far as relates to this plant is connected only with a series of 

 blunders, was abandoned by the autlior liiniself, and has since been applied to another ge- 

 nus already generally adopted. It may be distinguished by the following character,, and 

 named 



Pbtrobium. 



Involucrum polyphyllum subdupKci serie : exteriore breviore, foliolis paucioribus. ife- 

 cep/acaiuOT paleaceum, planiusculum. F/wa//idioici, tubulosi, 4-fidi : MascuU : Anthe- 

 ris exsertis ; Stigmatibus acutis hispidulis : Feminei : Staminibus sterilibus; Stigmatibus 

 acutis recurvis. ylchenium v. parallelo compressum v. angulatum; angulis (2-3) aristatis i 

 aristis perststentibus, antrorsum denticulatis. 



Arbor (Insulae S'^Helenae). FoUa. oppoiita,indivisa. Vamcv\a.terminalis,lirachiata. In- 

 volucrum ohlongum. Palex receptaculi squamis involucri sulsimiles. Corollulae ochioleu- 

 cae, tulto arcuato-rccurvo {ut capitulum primo intuitu radiatum videatur). Mas. Antheris 

 nigricanlil'us, bast emarginatis, appendice apicis brevissimo, aculo ; locutis vestigio septi 

 longitudinalis inslructis. Fern. Stamiaibus sterilibus distinctis, antheris sagitlatiscasais. 



VOL. XII- ti ia 



