NOTES ON OUR INDIANA DODDERS. 
T. G. YUNCKER. 
Dodder is the popular or common name ordinarily applied to species of 
Cuscuta. This genus belongs naturally to the Convolvulaceae. The re- 
markable embryogeny; the structure of the mature plants; the manner in 
which they secure their nourishment and their peculiar ecological rela- 
tionships make them subjects of particular scientific interest. 
There are in North America about fifty known native and five intro- 
duced species. Of the natives less than a half dozen are reported as harm- 
ful to economically important 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 repute. Some authors, however, attempt to show 
that the harm done by a few members of the group is offset by the good 
done by the others in parasitizing harmful weeds and thus retarding their 
growth. 
In the state of Indiana we have seven native and possibly two introduced 
species. Of these, one native, C. pentagona, and both of the 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 
eareful 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 trouble 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 visible 
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 species). 2. 
Stigmas linear. (Introduced species). 8. 
a. Flowers subtended by numerous bracts and ordinarily in a close, compact in- 
florescence. 3. 
Flowers not subtended by bracts and ordinarily in a more loosely clustered 
inflorescence. 4. : 
8. Inflorescence dense, rope-like, tightly wound about the host; bracts acute with 
TEC HO!) A OSh aia gle oro Bi chg Olas Saminyold caduowe enc Cus ioicieee m Gupiees 1. Cuscuta glomerata, 
Inflorescence less dense and not particularly rope-like; bracts obtuse, closely 
BPD CESRCUM GE RR eee Sec oe <i earn rem ie | OUSCUEE compacta. 
4. Flowers commonly 4-parted (or 3-parted). D. 
Flowers commonly 5- parted. ike 
5. Withered corolla remaining more or less persistant as a cap at the apex of the 
capsule ; infrastaminal scales well developed .......3. Cuscuta ( ‘ophalanthi. 
Withered corolla remaining at the base of the capsule, about it, or early decid- 
uous; infrastaminal scales rudimentary. 6. 
