Monotropaceae with Reference to Ericaceae 45 



Ericaceae (including as a tribe the Pyroleae), and the Mono- 

 tropeae. Drude (12) gives two families — the Ericaceae and 

 the Pyrolaceae (including the Monotropaceae). Britton and 

 Brown (6) consider as separate families the Pyrolaceae, Mono- 

 tropaceae, Ericaceae, and Vacciniaceae. Small (72) considers 

 the Pyrolaceae, Monotropaceae, and Ericaceae as distinct 

 families. So we see that the Pyrolaceae and Monotropaceae 

 are united by the majority of systematists, yet the gulf between 

 the two is really more difficult to bridge than that between 

 the Ericaceae and Pyrolaceae. 



Drude in "Die Natiirlichen Pflanzenfamilien" (12) gives as 

 his reasons for not including the Pyrolaceae and the Mono- 

 tropaceae in the Ericaceae: (1) the remarkable placentation, 



(2) the regular form of the seed and embryo in the Ericaceae, 



(3) the lacking disc, (4) the dehiscence of the anthers, (5) the 

 simple pollen of the Monotropeae. 



(1) In typical Ericaceae the ovary is five- or four-celled 

 with a central placenta. Two lobes bearing the ovules extend 

 into each cell of the ovary. It is generally considered to be 

 five-celled in the Pyrolaceae also, but the division is not com- 

 plete. The parietal placentae borne in on the dividing walls 

 fuse at the center for about half the length of the ovary. This 

 basal half is exactly similar to that of the Ericaceae, two pla- 

 cental lobes bearing ovules extending into each cell. Above 

 this the placentae fail to meet at the center and the upper half 

 becomes one-celled with bilobed parietal placentae. This con- 

 dition is true of C. umbellata, C. maculata, P. rotundifolia (P. 

 americana Sweet), P. elliptica, P. secunda* P. minor, P. chlor- 

 antha, P. aphylla, Moneses uniflora* of the Pyrolaceae; also of 

 Allotropa virgata, Pterospora andromedea, Sarcodes sanguinea, 

 Schweinitzia odorata, Monotropa hypopitys, M. uniflora, of the 

 Monotropaceae. The division Pleuricosporeae of the Mono- 

 tropaceae is considered one-celled in the ovary. Newberrya 

 is described by Torrey in the Ann. Lye. N. Y. VII 55 (1864): 

 "Placentae four with broad divergent lamellae which meet 

 adjacent edges, ovuliferous both sides giving the appearance of 



* P. secunda and Moneses uniflora are almost completely five-celled. 

 Owing to the sunken style the distance through which the ovary is one- 

 celled is very short. 



