TORREYA 



Vol. 41 



November-December, 1941 



No. 6 



Gametophytes of Equisetum Arvense L. 



Edwin B. AIatzke 

 (with four figures) 



Gametophytes of various genera of the common ferns, Filicales, 

 can be found without great difficulty in the field by searching in 

 appropriate habitats — in moist shaded woodlands in proximity to 

 mature sporophytes that discharge spores. Presumably the spores 

 of Equisetuin, the horsetail, often travel greater distances, and game- 

 tophytes are discovered very infrequently. The finding of large 

 numbers of the prothallia of E. arvense under rather unusual cir- 

 cumstances, and a brief description of these gametophytes, therefore 

 seem worthy of record. 



Miss Walker (1921, 1931, 1937) has made exhaustive studies of 

 the gametophytes of several species of Equisetum growing both 

 under natural conditions and in culture. This work has thrown 

 much light on the general nature of the gametophytes and especially 

 on the sexual expression of the haploid generation. Miss Walker 

 states that the finding of the gametophytes in nature "has been 

 rare." A few specimens of E. arvense gametophytes were found by 

 N. F. Petersen in 1917 at Osborn, Indiana (Walker 1921). Later 

 Miss Walker (1931) found abundant material of this species at one 

 other station, near Weeping Water, Nebraska, where the gameto- 

 phytes occurred "on moist clay soil situated in a small bend in a 

 creek." Miss Walker grew gametophytes of Equisetum arvense in 

 culture, from spores, and studied the production of antheridia and 

 archegonia in detail. 



The same species has been studied and collected in the field in 

 Europe in recent years by Mackel (1924) and Schratz (1928), both 

 of whom were interested in the sexual expression of the gameto- 

 phytes. Small male prothallia were found in the field by Schratz but 



ToRREYA for November-December (Vol. 41 : 181-217) was issued December 



19, 1941. 



181 



