370 T. Holm — Triadeniim Yirginicum (Z.) Rafin. 



remarkable, however, in the ^enus Hypericum^ but to a critical 

 student it would appear as if there might be some good reason 

 for suspecting additional, and perhaps more valid, characters to 

 accompany those, already pointed out by Kafinesque ; and from 

 the writer's observations upon this plant in a living state 

 through several seasons, Triadenum has proved to be quite an 

 interesting plant and undoubtedly a good genus. 



The flesh-colored flower attracted our attention when we 

 saw the plant for the flrst time, growing in a swamp in com- 

 pany with Rhexia^ Asclepias, Ey^iocaulon and others, and 

 when we examined the parts underground, we found a rhizome, 

 which was very different from that of other species of " Hyperi- 

 cum^^ as far as known. A continued study of the plant from 

 seedling and of the subterranean organs in connection with an 

 anatomical investigation of the vegetative organs compared 

 with those of other members of Hypericacece, and quite espe- 

 cially of Hypericum^ has convinced us that Triadenum pos- 

 sesses sufficient morphological and anatomical characters to 

 entitle it to a genus. In presenting the results of our study, 

 we will begin with some notes upon the morphology of the 

 plant which have not been hitherto recorded. 



In the seedling stage, Triadenum F^>^m^^wm does not differ 

 from most of the species of Hyijericum except in the very 

 characteristic glaucous hue of the leaves. There is a primary 

 root, a short hypocotyl and a pair of small cotyledons above 

 ground. The seedling reaches the flowering stage commonly 

 in the flrst summer, and ripens the seeds late in the fall, while 

 the main axis dies off during the winter. Nevertheless the 

 plant is perennial, for during the flowering period the basal 

 stem-portion has commenced to ramify, and shows from one to 

 two pair of horizontal branches, stolons, which are developed 

 in the axils of the cotyledons and the subsequent pair of leaves. 

 The former, those that arise from the axils of the cotyledons, 

 are characteristic by their somewhat swollen and short inter- 

 nodes, and small, membranaceous, scale-like leaves ; they ramify 

 freely, but are rootless for several months (T in figures 1 and 

 2) ; their color is crimson or yellowish brown. The other 

 stolons (St. in figure 2), which develop further up the stem, 

 have longer internodes, and are not swollen, and as a rule they 

 do not ramify. When we examine the plant in the succeeding 

 early summer, the main axis, including the main root (R in 

 figs. 1 and 2) has died off altogether, while several vegetative 

 or already flowering shoots have developed. from the stolons; 

 and when these aerial shoots finally die off during the fall, the 

 remaining part of the tuberous stolon is able to continue its 

 ramification for at least another year. 



Triadenum Virginicum thus possesses an underground 



