10 ILLINOIS BIOLOGICAL MONOGRAPHS [100 



2. Styles clavate Epilinella 



3. Style Single, capisate, ovoid Monogynella 



Capsule not circumscissile. Tribe C'lisnitinene 



4. Styles capitase, globular Cassutha 



5. Styles filiform; seeds winged Succuta 



Des Moulins carefully considered the morphological details of the plants, 

 but was at an apparent disadvantage on account of the limited number 

 of species, about fifteen, known to him. 



Engelm.ann, in 1859, after over twenty years of study in this country 

 and abroad, published his Systematic Arrangement of the Species of the 

 Genus Cuscuta. He considered the whole group as belonging to one 

 genus of the Convolvulaceae which he divided into three sub-groups or 

 sections. The first, comprising those species with linear stigmas and 

 distinct styles, he called Cuscuta; the second, those species with distinct 

 styles and capitate stigmas, Grammica, and the third, those with the styles 

 more or less united and the stigmas of various shapes, Monogyna. These 

 three groups he in turn divided into nine sections, including seventy-seven 

 species, sixty-one varieties and four sub-varieties. 



Engelmann had seen nearly all of the collections in the European and 

 American herbaria and was able to relegate to synonymy a great many 

 names that had been exercising botanists for many years. His ideas 

 concerning the classification of these plants were well founded and, even 

 in the light of present day knowledge, one finds it difficult to offer con- 

 sistently any radical changes or improvements on his arrangement. 



MATERIAL AND METHODS 



The work, the results of which are recorded here, was carried on at 

 the University of Illinois during the years 1917 to 1919 inclusive. Some 

 time was spent in the libraries at Washington, D. C. and in studying the 

 materials in different herbaria. 



The studies were all made from dried herbarium specimens. It is 

 possible that fresh specimens will show some variation from the descriptions 

 given because of shrinkage and alterations attendant upon drying, but 

 this can scarcely be avoided. The specimens were prepared for study 

 in one of two ways. They were either soaked in a lacto-phenol solution^ 

 which is admirable for bringing the structures back to near their normal 

 shape, or boiled in water. In either case the flowers were placed in water 

 for study to prevent the collapsing of the parts. The objection to the 

 use of the lacto-phenol solution is that it is necessary to leave the materials 

 in it for some time (usually at least 48 hours) before they are soft enough to 

 dissect. This is not the case, of course, with boiling when they can be 



1 Lacto-phenol stock solution : glj'cerine 40 parts; latic acid 20 parts; phenol crystals 

 20 parts; water 20 parts. 



