2 MINNESOTA STUDIES IN PLANT SCIENCE 



carpels and the gland (or disc). The result is a more or less unnatural 

 grouping based on minor characters. We thus find a collection of species 

 of widely different affinities, as for example where Sa^ifraga erosa Pursh 

 {Saxifraga micranthidifolia Haw.) is grouped with Saxifraga Forbesii 

 Vasey, and where Saxifraga hieracifolia. W. and K. is grouped with Sax- 

 ifraga pennsylvanica L. and Saxifraga integrifolia Hook. (See sections 

 Aulaxis, Micranthes, and Chionophila^ respectively, in this paper.) 



Turning now to the early work of Haworth (13) we find in that 

 writer's Synopsis Plantaruni Succulejttarum the first attempt to break up 

 the Linnaean genus Saxifraga, a task which he carried out more fully in 

 his later Saxifrage arum Enumeratio. In the latter work Haworth (14) 

 made sixteen genera out of the old one, retaining the name Saxifraga for 

 one of the genera. Without dwelling on the details of Haworth's work it 

 may suffice to state that he pointed out, a century ago, the fundamental 

 taxonomic distinctions between certain species which Engler many years 

 later embodied in the section Boraphila. Haworth first clearly rec- 

 ognized the significance of epigyny and hypogyny in the classification of 

 the species then known, and on these characters he based his generic dis- 

 tinctions. To illustrate, in establishing the new genus Aulaxis on the species 

 Aulaxis {Saxifraga^ micranthidifolia Haw. {Saxifraga erosa Pursh) 

 Haworth clearly recognized the value of the characters of the carpels, as 

 witness his description : "cdpsulae superae cite bipartitae hasi solum coalitae, 

 in restora acuta suhdivaricato progredientes." The accuracy of his observa- 

 tion will be appreciated by referring to the figure of Aulaxis in Plate I. It 

 is strange that these characters should have escaped the notice of subsequent 

 investigators. 



Of Haworth's other genera, including species with which we are here 

 concerned, Micranthes was reduced to sectional rank by D. Don (3), 

 Tausch (30), and Seringe (26), and later by Torrey and Gray (31), 

 and by Hooker (16). The genus Rohertsonia was reduced to sectional rank 

 by Engler (4). In a recent work of Small (27) Haworth's genera 

 Micranthes and Spatularia are restored. 



D. Don (3) grouped the species in two sections, Gymnopera and 

 Micranthes, basing the distinctions on the characters of the calyx. Thus 

 the calyx of the former section was described as "reflexed," that of the 

 latter as "spreading." Along with these he included descriptions of tlie 

 stamens and the carpels. Since the "reflexed" and the "spreading" condi- 

 tions of the calyx are characteristic of hypogynous and epigynous species 



' Chionophila sect. nov. Receptaculum ovario alte adnatum; folHcuH clHptico-ovati pl^s 

 irinusve inflati superne conspicue contract!, stylis plus minusve elongatis saepe crasslusculis, stig- 

 matibus globosis vel discoideis; glandula discoidea, margine inferiore calycis basi approximata; fila- 

 menta subulata plana ad aspicem incurva antheris oblongis; sepala patentia semina angusta ovata 

 margine minime alata plus minusve striata. 



