ON THE GENUS ISOETES. 



[Read before the Society by Mr* E. D* Marquand, May 1st, 1889.) 



A fortnight ago Mr. Derrick most kindly sent me up fresh 

 specimens of the Guernsey Isoetes, which I was much pleased 

 to have an opportunity of examining, for it is by no means a 

 conspicuous plant, and one might search a long while without 

 lighting upon it. As you all know it is one of the great prizes 

 of our island Flora, like Ophioglossum lusitanicum, Lagurus 

 ovatus, Orchis laxiflora, and several other plants which are 

 peculiar to Guernsey. As I had occasion to read up the litera- 

 ture of the subject in such books as I happen to have on my 

 own book- shelves, it occurred to me that a short paper on this 

 genus of very singular cryptogams would not be out of place 

 this evening, and possibly would prove of interest to the mem- 

 bers present. 



There has been among botanists more or less uncertainty 

 about the exact and proper position of this genus Isoetes, on 

 account of its very extraordinary fructification, but all are 

 agreed that it is allied to the Lycopods or Club Mosses, 

 although very alike them in habit. English systematists all 

 place Isoetes in the Lycopodiacese, whilst the continental 

 ones have formed a distinct order for its reception, Isoetacce, 

 and I am incline to think they are right. 



I need not give you the generic characters of Isoetes, as you 

 may find them in any text book, but I wish to call your atten- 

 tion to the species which are comprised in it, since it is our 



