38 The Ottawa Naturalist. [May 



white. t To every one knowing American meadow rues such 

 an expression will seem to point to something belonging to the 

 group of T. polygamum; yet when he assures us that the plant 

 he has in mind is hardly a foot high, and is also distinguished 

 from all other members of the genus by a drooping foliage, we 

 seem to see that he probably had something of this T. dioicum 

 sort before him. 



I have met with no good evidence that this type of 

 Thalictrum was known before Kalm; though Philip Miller says 

 that Parkinson grew the plant a hundred years earlier. J I can 

 not, however, verify this by anything which I find in Parkinson. 



Out of that multitude of things which, while answering to 

 the Linnaean account of the size and habit of T. dioicum, are 

 still widely dissimilar among themselves in essential marks of 

 flower and fruit, it is necessary that some one marked type be 

 selected, and that of necessity arbitrarily, to be described, as not 

 one of them ever yet has been, with something approaching 

 fulness and precision. To such a type, though arbitrarily 

 chosen from among others, the name T. dioicum mav l)e assigned, 

 according to the now prevailing custom ; though from several 

 points of view it would seem wiser to abandon that name 

 altogether, as one that has never been adequately published. 



Thalictrum dioicum. Thalictrum dioicum, Linn., Sp. PI. 

 545. Stem solitary, 1-2 feet high, upright from a tuft of fleshy- 

 fibrous widely spreading and not deeply seated roots; leaves 2 

 or 3, ample for so small a plant, long-petioled, thin and delicate, 

 deep-green above, pale beneath, glabrous; terminal leaflets in 

 maturity 1 inch broad or more, of suborbicular outline, commonly 

 with subcordate base, the length seldom quite equalling the 

 breadth, primary lobes 3, reaching to near the middle, the 

 central one broadly equally and shortly 3-lobed, the other two 

 unequally 2-lobed, or sometimes entire, all lobes short and very 

 obtuse; lateral leaflets smaller, in general 3-5-lobed with little 

 or no distinction of primary and secondary lobes: staminate 

 plant with fewer flowers and less ample inflorescence than the 

 pistillate, its sepals 4, oval, obtuse, thin, pale, often purplish- 

 tinged, delicately parallel-veined; anthers green, not quite as 

 long as the purplish filaments, linear, acutely rather long- 

 pointed: achenes rather light-green, less than 5 mm. long, of 

 soraewhat obliquely elliptic outline, the about 10 ribs thick 

 but acutely edged, the furrows between them as broad and 

 acute. 



Billings' Bridge, Ottawa, Ont., J. M. Macoun, 12 May, 1891, 



t Linn. Sp. PI. 545. 



X Mill. Diet. Ed. vii (1749). 



