694 Rydberg : Rocky Mountai'n flora 



The typical Orobanche has the calyx characteristic of, for instance, 

 Castilleja in Scrophulariaceae, /. e., the calyx is deeply cleft in 

 front and behind, with the lateral divisions entire or 2-cleft. None 

 of our native American plants has this structure. They have all 

 (except those included in Boscliniakia by Gray) an almost equally 

 5 -toothed calyx. There is a group of Old World plants, of which 

 OrobancJic purpurea ^nd 0. rauiosn are introduced into this country, 

 which have a 4-toothed or only occasionally 5 -toothed calyx, but 

 in that case the upper tooth is much smaller. In Gray's New 

 Manual the former is described as having a " 5-lobed " calyx. 

 This is only occasionally the case. These species constitute the 

 genus Kopsia Dum. or PJuiipaea Nees (not Desf.). The writer 

 thinks that the five sections of Beck's monograph should be re- 

 garded as genera. MyzorrJiiza Philippi is the only available name 

 for Aphyllon § NotJiaphyllon Gray. This genus differs from TJialcsia 

 in habit and in the arrangement of the placentae, from Crobanclie in 

 the regularly 5-toothed instead of 2-cleft calyx, and from both in 

 the presence of bractlets. The type oi th^ genus is 



Myzorrhiza CHiLENSis Philippi, Linnaea 29: 36. 1857 

 Orobanche chilensis G. Beck, Bibl. Bot. 4 : 82. 1890. 

 This is closely related to our most common North American 

 species : 



Myzorrhiza ludoviciana (Nutt.) Rydb.; Small, Fl. SE. U. S. 



1093. 1903 

 Orobanclic ludoviciana Nutt. Gen. 2 : 58. 1818. 

 PJielipaea ludoviciana Walp. Rep. 3 : 46 1 . 1 844 . 

 Aphyllon ludovicianuui A. Gray, Bot. Calif, i : 585. 1876. 

 '^Aphyllon arenosuni Suksd. AUg. Bot. Zeits. 12: 27. 1906. 



given for the two first are correct ; there are three scales under the flower, one bract 

 and two lateral bractlets ; Orobanche minor has one bract and no bractlets, while O. 

 ludoviciana has 1 or 2 bractlets under the flower. It has exactly the same arrangement 

 as O. purpurea and O. rainosa, except that one of the bractlets is sometimes lacking 

 and the bract is usually some distance below the calyx. Orobanche uniflora and O. 

 fasciculata are not without bracts. They are without bractlets, but the bract is found at 

 the base of the longer pedicel. They are like 0. minor (a typical Orobanche) in hav- 

 ing no bractlets, but differ in the 5-toothed instead of 2-cleft calyx. O. ludoviciana 

 has bractlets and should have been associated with the two first species, if the presence 

 or absence of bractlets was taken as the dividing character. In all the species the 

 bracts are present although situated at different distances from the calyx, depending 

 upon the length of the pedicels. 



