The USDA plant site shows fifty species (in the U.S.) for the Genus Cuscuta (dodder). Ten species are shown in Iowa. Nine, including C. compacta (compact dodder), are shown as native and one, C. epithymum (clover dodder), as non-native (alien).
BONAP (The Biota of North America Program) shows fifty-four species in the U.S. with eleven species in Iowa including C. megalocarpa (bigfruit dodder). Ten species are native and one, (C. epithymum) is alien.
In The Vascular Plants of Iowa (1994) Eilers and Roosa report eight native species in Iowa: (C. cephalanthii, C. coryli, C. cuspidata, C. glomerata, C. gronovii, C. indecora, C. pentagona, and C. polygonorum).
C. glomerata is noted as frequent in S.E. Iowa, the other seven species are rated as infrequent to rare.
A ninth species, C. megalocarpa (bigfruit dodder), is shown by BONAP to occur in two counties in Northern Iowa. The taxonomy of this species is presently uncertain so it won't be discussed here except to offer these few links:
1, 2, 3, 4, 5, 6, 7. The FNA should have this worked out soon.
Cuscuta species are parasitic on other plant species and are believed to be non-photosynthetic.
The Cuscuta species that have been reported in Iowa are:
Cuscuta cephalanthi - (buttonbush dodder)
Cuscuta coryli - (hazel dodder)
Cuscuta cuspidata -(cusp dodder)
Cuscuta glomerata - (rope dodder)
Cuscuta gronovii - (scaldweed)
Cuscuta indecora - (bigseed alfafa dodder)
Cuscuta pentagona - (fiveangled dodder)
Cuscuta polygonorum - (smartweed doddder)
Time lapse video showing dodder entwining host.