Xo'l'KS (».\ (MR IMUAXA I »n| H MM.'S. 

 T. (i. Vr.\( KKii. 



Dodder is tlio popiilMi- or (•(iiiiimiii iinim' oi'diii.-ii'ily iii)|>licil to siiccics of 

 CiisckIh. This Ki^nis bcloiij^s iiiiturally to tlic Coiivolvulaccat'. 'I'lic rc- 

 iiiarlviihlc eiulti-.voycny ; the structure of the mature plants: thi- manner in 

 which they secure tlieir nourislnnent and tlieir peculiar ecolof^ical rela- 

 tionships make them suhjects of parlicular scientific interest. 



There are in North America al)ont tifty known native and five intro- 

 duced siK'cies. ( »f the natives less tlian a half dozen are reiwrted as hai'm- 

 ful to eeononiically iiu|)ortant crops, and, of these, but one or two are of 

 much importance. Of the introduced species four are distinctly harmful. 

 Because of the trouble caused by this minority the whole genus is fre- 

 quently considered in ill rei)ute. Some authors, however, attempt to show 

 that the harm done by ;i few members of the liroup is offset liy the good 

 done by the others in parasitizing harmful weeds and thus retarding their 

 growtli. 



In the state of Indiana we liavc seven native and ]>ossil»ly two introduced 

 si)ecies. Of these, one native, V. pcniagona, and both of tlie introduced spe- 

 cies are harmful to crops. The amount of harm caused by these parasites 

 becomes considerable if they are not checked, in some cases causing nearly 

 the total loss of the crop. The grower finding these plants in his fields 

 should take immediate steps to destroy them. 



In the proper identification of the species one must ordinarily make a 

 careful dissection of the flowers. After the flowers have been pressed and 

 dried this usually means that they require softening by boiling and the 

 subsequent dissection in water. Because of the lack of other vegetative 

 characters of diagnostic value and the troulile attendant on the flower 

 dissection many of the collections show no attempt at all towards identifica- 

 tion. Certain species frequently show wide specific limitations that is apt 

 to confuse one not perfectly familiar with the genus. The nomenclature of 

 the group is also quite confused. 



It is believed that a key using those characters that are ordinarily \isible 

 with the aid of a hand lens will be of value. The following key aims at 

 the identification of the species found in Indiana without the necessity of 

 making flower dissections. 



1. Stigmas capitate. (Native speciesK 2. 

 Stigmas linear. (Introduced species). S. 



2. Flowers siil)t('n(lt'(l l)v iuuiktuiis liijicts and urdinarily in a close, compact in- 



florescence. :',. 

 Flowers not suliteiideil liy bracts .iiid cirdiiiaiily in a iiKire loosely clustered 



inflorescence. 4. 

 .3. Inlloiescence dense, rope-like, tightly wound about the host ; bracts acute with 



reciirved f ips 1. Cusciita glomcruta. 



Inllorescence less dense and not particularly rope-like; bracts obtuse, closel.v 



appressed 2. Ctisvuta compavla. 



4. Flowei-s cnniiiKinly 4-parted (or 3-parted). .">. 

 Flowers cdimiKiiily 5-parted. 7. 



5. Witliered ccircdla renniining more or less persistant as a cap at tlie apex of the 



capsule : intrastaniinal scales well devtdoped :!. Ciisciila ('rplialanihi. 



Withered corolla remaining at the Itase ot' llie capside, altout it, or early decid- 

 uous; iiifi-a.staiiiiiial scales rudiineiifary. (i. 



