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MONOGRAPH OF THE ISOETACEAE 1 



NORMA E. PFEIFFER 

 Associate Professor of Botany, University of North Dakota 



HISTORY 



The name Isoetes was first mentioned by Linnaeus in 1751 

 (Skanska Resa, 417, fig. 1), although the common European 

 species of the group had been previously known for many years 

 and variously recorded under different names. In 1753 Linnaeus 

 (Species Plantarum 2: 1100) definitely established the genus 

 Isoetes, as follows: 



lacustris. ISOETES. It. Scan. 417. *. 419. Nov. gen. 1109. 

 Marsilea foliis subulatis semicylindricis articulatis. 

 Fl. suec. 996. [Stockholm, 1745]. 

 Calamaria folio longiore & graciliore. Dill, muse, 

 541. *. 80. /. 2. [Oxford, 1741]. 

 Subularia lacustris f. Calamistrum herba aquatica 

 alpina. Raj. angl. 1. p. 210. t. 210. [London, 

 1677]. 

 Habitat in Europae frigidae fundo lacuum." 



^ o In the following year Linnaeus (Genera Plantarum, 486. 



i a 754) characterized the genus, relating the structures to those of 

 3ZZI eed plants. The male flowers were described as solitary within 

 base of inner leaves, with no corolla, but with a calyx of cordate 

 sales, acute and, sessile, and with stamens having subrotund, 

 unilocular anthers, but no filaments. The female flowers were 

 reported as solitary, within a base of outer leaves of the same 

 plant, with the calyx and corolla situation as in the male. The 

 pistil was described as having an ovate embryo within a leaf, but 

 the style and stigma were supposed to be hidden. The fruit was 

 considered to be a capsule, subovate and bilocular, concealed in 

 the base of the leaf, and the seeds to be numerous and globose. 

 In an earlier account (Skanska Resa, 417. fig. 1. 1751), Linnaeus 

 expressed jubilation over finding flowers, whereas Dillenius had 

 seen only fruits. 



1 Special investigation carried on mainly at the Missouri Botanical Garden. 

 Issued Nov. 27, 1922. 

 Ann. Mo. Bot. Gard., Vol. 9, 1922. 



