8 PROCEEDINGS OF THE AMERICAN ACADEMY 



n. 



NOTES ON SOME NORTH AINIERICAN SPECIES OF 



SAXIFRAGA. 



By Asa Gray. 



Communicated June 11th, 1884. 



Saxifraga peltata, Torr. Peltiphyllum, Engler, is an appro- 

 priate name for tliis very distinct section, which certainly connects 

 Sergenia of Moench with the true Saxifrages. Apart from the very 

 thick and much-creeping rhizome, which is that of Bergenia exaf^orer- 

 ated, and the huge peltate leaves, which are peculiar, the section is 

 marked by its roundish and rotately spreading and promptly deciduous 

 petals, reflexed calyx, and comparatively large (a line long) and loose- 

 coated seeds. As to the distinction made by Engler, that the flowers 

 of Bergenia are protogynous and those of Saxifraga protaudrous, 

 I remark that, while most plants of S. peltata are protandrous, some 

 of our native specimens are either truly protogynous in the sense that 

 their anthers are later than the stigmas, or their stamens are reduced 

 in size and probably in efficiency, that is, the flowers show a ten- 

 dency to be gyno-dioecious. Engler's mistake in placing his section 

 Peltiphyllum under a division with capsule dehiscent only at the upper 

 part, has been corrected in the Botanical Magazine and in the Botany 

 of California. His " rhizoma crassiusculum " is not much improved 

 by "rootstock as thick as the thumb" in the Botanical Magazine. 

 Even in cultivation, with us it attains the diameter of " from two 

 to three inches." The divisions of the calyx are neither erect, nor 

 shorter than the tube, but reflexed in anthesis and very much longer 

 than the tube, if tube the consolidated base can be called. Bentham 

 described the petals as marcescent, and Torrey as persistent ; but in 

 fact they are early deciduous. The absence of bracts was noted by 

 Bentham, and is used as a sectional character by Engler. But bracts 

 subtending the branches of the panicle do occasionally occur, just as 

 they do in the section Bergenia. The carpels in our cultivated plant 

 are turgid in fruit, just as in Dr. Torrey 's figure, but commonly more 

 elongated. 



