On the characters and relationships of the Platanaceae "^^ 



Robert F. Gkiggs 

 (with plate 25) 



1 



Recent writers under the leadership of Niedenzu (i) in the 

 Engler and Prantl Pflanzenfamilien have agreed in placing the 

 Platanaceae in the Resales between the Saxifragaceae and the 

 Rosaceae. But as to the characters of the family, which of course 

 form the basis of all deductions concerning its relationships, there 

 is no agreement. This is very strikingly brought to notice by 

 comparison of two leading floras recently published almost simul- 

 taneously. Robinson and Fernald in Gray's New Manual (2) 

 state that the flowers are ''destitute of calyx and corolla" while * 

 Gleason, (3) describing the Platanaceae in the North American 

 Flora, attributes both calyx and corolla to the flowers. 



Neither of these authors is to be held accountable for the 

 statements in his description, for both are undoubtedly compila- 

 tions from older authorities. Indeed, Robinson and Fernald's de- 

 scription is copied verbatim from Gray's fifth (4) and sixth editions 

 published as long ago as 1867. But since the appearance of the 

 Pflanzenfamilien in 1891, which figured and diagrammed the 

 flowers as having both petals and sepals, almost all writers have 

 credited the flowers with them and have described them, some- 

 times in considerable detail. Of these descriptions that of Sar- 

 gent (5) will serve as an example. ** Calyx of the staminate 

 flower divided into ^-6 minute scale-like sepals slightly united at 

 the base, about half as long as the ^—6 cuneiform sulcate, scarious 

 pointed petals ; stamens as many as the divisions of the calyx, 

 opposite them, . . . ; calyx of the pistillate flower divided into 

 ^_5^ usually 4 rounded sepals much shorter than the acute petals; 

 stamens scale-like, elongated-obovate, pilose at the apex; ovaries 

 as many as the divisions of the calyx, superior. . . ." And in his 

 Silva (6) he gives figures and floral diagrams showing these parts. 



* Contributions from the Botanical Laboratory of tLe Ohio State University, No. 



XLVII. 



389 



