T. Holm — Triadenum Virginicum (Z.) Eafin. 369 



Art. XXX YI. — Triadenum Virginicum (L.) Rafin. A 

 morphological and anatomical study ; by Theo. Holm. 

 (With figures in the text.) 



There are said to be. at least thirty generic synonyms of 

 Hypericum^ of which Spach is the author of nineteen ; Hyveri- 

 cum L. is, however, the only one recognized by Bentham and 

 Hooker, while the other genera are treated merely as sections 

 of two large groups : in accordance with the presence or absence 

 of hypogynous glands in the flower. The suppression of these 

 proposed genera may in some instances seem justified, since not 

 a few of the writers who have dealt with the segregation of 

 genera, and especially of small ones, have perhaps gone too far 

 in their discrimination, or they have not always expressed their 

 reason for making these segregations as clearly as might be 

 desirable. But whatever the case be, a renewed study of 

 several of these segregations may lead to their reestablish men t, 

 especially after careful observations in the field, rather than by 

 continued research in herbaria. 



Moreover, in late years the anatomical method has rendered 

 great assistance by the supplementing of characters derived 

 from the internal structure. The actual value of such anatomi- 

 cal' characters is, however, only to be perceived when the 

 structure of most of the species of a given genus is known, and 

 we believe that, for instance, the Hypericace(Bh2iVQ been studied 

 thoroughly from this point of view to enable us to draw certain 

 distinctions between the genera. 



In presenting a study of the genus Triadenum, it is the 

 writer's intention to demonstrate the validity of one of the 

 obscure genera of Rafinesque, which has, as it appears, been 

 imperfectly known heretofore, and ignored by most authors, 

 even by Bentham and Hooker. The history of the genus is 

 very brief. Rafinesque removed Linnseus's Hypericum Vir- 

 ginicum from the genus and referred it to a new genus Triade- 

 num, on account of the presence of three glands in the flower, 

 alternating with the stamens. Triadenum Virginicum (L.) 

 Rafin. is also known under the name Elodes or Elodea Vir- 

 ginica, but this genus, established by Adanson, does not include 

 plants of habit or structure like that of Triadenum. Finally, 

 Hypericuyn Virginicum, as described in the Synoptical Flora,"^ 

 is our plant, and it so happens that we have not reached a 

 single step farther in regard to the classification of this plant 

 than at the time of Linngeus. 



It is true that Rafinesque founded his genus Triadenum on 



no other characters than the floral glands and reddish flowers, 



* For references consult tlie Bibliography appended to this paper. 



Am. Jour. Sci. — Fourth Series, Vol. XVI, No. 95. — Noyember, 1903. 

 26 



