20 ILLINOIS BIOLOGICAL MONOGRAPHS [110 



SYSTEMATIC ARRANGEMENT OF THE GENUS 



CUSCUTA (Tournefort) Linnaeus 



Cuscuta Tournefort, Inst. ReiHerb., 1:652, t. 422, 1700. Linnaeus, Spec. PI., 124, 1753. 

 Chois)^, Mem. Soc. Phys. et Hist. Nat. Geneve, 9:268, 1841; and in DC, Prodromus, 

 9:452, 1845. Engelmann, Trans. Acad. Sci. St. Louis, 1 :453, 1859. Bentham & Hooker, 

 Gen. PL, 2:881, 1873. Peter, in Engler&Prantl, Die naturl. Pflanzenfam., Teil IV, 

 Abteil. 3a, p. 37, 1897. 



Epilhymum (Plinius ex) Nieuwland & Lunell, Amer. Mid. Nat., 4: 511, 1916. 



Hypogynous, sympetalous, herbaceous parasites. Stems filiform, twin- 

 ing about woody or herbaceous hosts from which they obtain their nourish- 

 ment by means of haustoria. Leaves reduced to small functionless scales. 

 Flowers small, more or less cymose clustered, mostly gamosepalous; 

 usually pentamerous (infrequently tri- or tetramerous) ; stamens inserted 

 in the throat, alternating with the corolla lobes; scale-like, more or less 

 fringed or fimbriate structures present in most of the species at the base 

 of the corolla opposite the stamens; ovary two-celled, each cell containing 

 two anatropous ovules; styles distinct or united; stigmas capitate or 

 linear-elongated. Fruit a capsule which remains closed or opens with a 

 distinct line of circumscission near its base; embryo acotyledonous, 

 filiform or with an enlargement at one end. 



Key to the subgenera 



Styles more or less united Monogyna(p. 20). 



Styles distinct. 



Stigmas linear-elongated Succuta (p. 21). 



Stigmas capitate Gr.'^mmica (p. 25). 



Sub-genus monogyna Engelmann 



Cuscuta group Monogyna Engelmann, Trans. Acad. Sci. St. Louis, 1:460, 1859. 

 Kadurias Rafinesque, Fl. Tellur., 4:91, 1836. 

 Aplostylis Rafinesque, Fl. Tellur., 4:91, 1836. 



Stems very coarse. Flowers sessile or on short pedicels in spicate, 

 racemose or paniculate cymes, pentamerous, the withered corolla remain- 

 ing at the apex of the regularly circumscissile capsule or dropping oflf; 

 styles thick, more or less completely united; stigmas capitate, subglobose 

 to ovate or conic. Chiefly parasitic on woody hosts. Mostly Old World 

 species, only one being found in North America. 



Section monogynella (Des Moulins) Engelmann 



Cuscuta section Monogynella (Des Moulins) Engelmann, Trans, Acad. Sci. St. Louis, 1:512, 



1859. 

 Monogynella Des Moulins, Etudes org. cusc, p. 65, 1853. 



Flowers in spicate or racemose cymes; stigmas capitate, subglobose or 

 ovate, on thick, more or less completely united styles; withered corolla 

 always remaining at the apex of the capsule. 



