[Vol. 9 



112 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Neyraut (Mo. Bot. Gard. Herb.) ; Montpellier, in pond of 

 the woods of Grammont, 10 June, 1889, Herb. Copineau (U. 

 S. Nat. Herb.); pond near Montpellier, 181)2, de la Per- 

 raudiere (Mo. Bot. Gard. Herb.); ponds of Roquehaute, 

 Herault, 15 May, 1895, Mandon (Mo. Bot. Gard. Herb.) ; 

 Portiragnes, Roquehaute, 2 May, 1896, Scnnen (Mo. Bot. 

 Gard. Herb.); Portiragnes, Herault, ponds in plateau of 

 Roquehaute, 6 November, 1897, Neyraut (Mo. Bot. Gard. 



Herb.); plateau of Roquehaute, May, 1898, Herbarium 



Nor male, I. Dorfler, {Neyraut) 3698, (U. S. Nat. Herb.) ; 

 Montpellier, Herault, 20 February, 1898, Mandon (Univ. 

 Minn. Herb.) ; Portiragnes, 8 May, 1898, Neyraut (Mo. 



Bot. Gard. Herb, and U. S. Nat. Herb.) ; Montpellier, in the 

 ponds of Grammont, X July, 1997, Societe Cenomane d'Ex- 

 siccata [Jean de Vichet] Jf.82 (Mo. Bot. Gard. Herb.) ; Lac 

 de Grand Lieu, 27 September, 1880, without collector (Mo. 

 Bot. Gard. Herb.); without locality or date, DeCandolle 

 (N. Y. Bot. Gard. Herb.). 



Historically one of the oldest species of Isoetes, I. setacea Bosc 

 was the subject of a detailed and interesting account by Delile, 

 who credited Bosc with the name for this species of central 

 France, as published in Dictionnaire d'Histoire Naturelle. The 

 lack of velum associated with the numerous small tubercles of 

 the megaspore and the rather firm but flexuous, fine leaves, make 

 distinctive points of difference between this form and the /. velata 

 series (complete velum), /. adspcrsa A. Br. (large warts on 

 smaller spores), and /. MdLinverniana Genn. (larger tubercles 

 on larger spores in much coarser plant). 



The distribution of peripheral strands is the most variable pos- 

 sible; most frequently there are six at the cardinal points, with 

 numerous other groups irregularly arranged beneath a much 

 thickened epidermal layer. Sometimes these groups are so nu- 

 merous as to make an almost continuous band. On the other 

 hand, the cardinal bundles may be very weak; or only four of 

 them may be developed ; or, most extreme situation of all, there 

 may be no development of these thickened cells. The different 

 possible arrangements may be found in the same plant, where 

 the base of the leaf shows no peripheral strands and the apex 

 a fairly strong development. Doubtless there is a response to 

 external factors. 



