parasitic vine is a summer annual up to several feet long that
branches occasionally. The stems are yellow to orange, more or less
terete, glabrous, and about 1 mm. across. These stems curl around the
stems of suitable host plants, climbing upward and often
smothering them. Sessile suckers (haustoria) occur along these stems at
frequent intervals, causing them to have a warty or bumpy appearance.
These suckers extract water and nutrients from the host plants. There
are no leaves and this vine does not produce chlorophyll; it is totally
dependent for survival on its host plants. As the vine continues to
grow, dense clusters of 5-25 flowers are occasionally produced. Each
flower is about 3 mm. across, consisting of a light green to yellowish
green calyx with
5 lobes, a white corolla with 5 triangular or ovate-triangular lobes
with incurved tips, 5 exserted stamens, and a light green to yellowish
with a pair of short styles with knobby stigmas. The glabrous calyx is
short-campanulate (bell-shaped) and each lobe either overlaps adjacent
slightly or it is non-overlapping. The circumference of the calyx is
circular (round), rather than angled.
Individual calyx lobes are usually oval in shape with obtuse or rounded
tips. Fertile anthers are up to 0.5 mm. in length and bright
yellow, becoming light brown as they wither away.
The pedicels of the
flowers are light green to yellowish green, glabrous, and very short
(0.5-2.0 mm. in
length). These pedicels are initially terete and about 1 mm. across,
but they may become swollen and angular as their flowers develop.
Sometimes solitary bracts occur at the bases of flower clusters, or
at the bases of individual pedicels. The blooming period occurs from
mid-summer to early fall, lasting about 1 month. The flowers are either
mildly fragrant or
not noticeably fragrant; in the absence of cross-pollination, they are
self-fertile. As the flowers continue to mature, their ovaries
(developing seed capsules) swell in size, becoming 2-3.5 mm. across and
subgloboid (depressed-globular) in shape. Immature seed capsules are
light green, becoming yellowish orange as they begin to mature, and
turning light brown to brown at full maturity. These capsules
eventually split open irregularly to release their tiny seeds (up to 4
seeds per capsule). The seeds can spread to other areas by wind or
water. Individual seeds are 1.0-1.5 mm. in
length, ovoid-angular in shape, and dull yellow to brown.
The seed surfaces are minutely pitted (requires 20x magnification
or higher to see). While an elementary root system develops from a
newly germinated seed, it soon withers away as the seedling becomes
attached to a host plant.
This parasitic vine
requires a suitable host plant in order to survive. Examples of such
host plants include Baptisia
(Blue Wild Indigo), Trifolium
(Sugar Beet), Solanum tuberosum
(Smartweeds & Knotweeds), Allium cepa
(Onion), and many others.
Unsuitable host plants include Glycine max
(Soybean), Equisteum arvense
(Field Horsetail), and
most grasses and sedges. Field Dodder occurs in drier
habitats than many other
(Dodder species). It is typically found in
either sandy or non-sandy areas where there is full sun or
partial sun. The seeds can persist in the soil and remain viable for
Field Dodder (Cuscuta campestris
throughout Illinois (see Distribution
), where it is native. Field Dodder is one of the more
common Dodder species in Illinois and
it is widely distributed in North America. Habitats include banks of
rivers, fields, croplands, neglected flower gardens, and waste areas.
This dodder is considered a significant pest of several field crops. It
is found primarily in disturbed areas.
(1929) observed small bees sucking nectar from the flowers of
(Dodder species), including Halictid bees (Lasioglossum) and
plasterer bees (Colletes). Such floral visitors appear to be uncommon.
Various aphids are able to suck juices from dodder vines and
successfully reproduce, weakening them substantially (Harvey, 1966).
Aphids that have adapted particularly well to these parasitic vines
include Aphis craccivora
(Cowpea Aphid), Macrosiphum
Aphid), and Myzus
(Green Peach Aphid). Mammalian herbivores
seem to avoid plants that are badly infested with dodder. These
parasitic vines may be toxic to such animals if they are eaten in
sufficient quantity. Nonetheless, should such animals consume these
parasitic vines with their host plants, the seeds of dodder can pass
through their digestive tracts and remain viable for several years.
Because the tiny seeds of these vines become
sticky when they are wet, they are probably spread to other areas by
the feet or fur of mammals, the feet or feathers of birds, and the
shoes of people. Agricultural machines may spread this vine
into different fields through the use of contaminated crop-seed.
Some materials that are used in gardens (e.g., contaminated mulch
& soil) may also facilitate its spread.
A flower garden at a city park in Champaign,
this dodder infested Baptisia
(Blue Wild Indigo).
Field Dodder (Cuscuta
) can be distinguished from some Dodder species
Illinois by the 5-lobed corollas of its flowers: the lobes of these
corollas have very acute tips that are incurved. A similar species,
Common Dodder (Cuscuta
), also has 5-lobed corollas, but the
tips of its lobes are more blunt and they are less incurved. Field
Dodder is also similar to Prairie Dodder (Cuscuta pentagona
This latter species has more angular calyces, while its seed capsules
are slightly smaller in size and less depressed in shape. Prairie Dodder
also has shorter anthers and shorter seeds. In the past, Field Dodder
was considered a variety of Prairie Dodder (Cuscuta pentagona
), but they are now regarded as distinct (Costea et
al., 2006; Costea et al., 2015). Other common names of Cuscuta
include Large-seeded Alfalfa Dodder and Golden
Dodder, while another scientific synonym of this species is Cuscuta