rope dodder

(Cuscuta glomerata)

               
Conservation Status

IUCN Red List

not yet assessed

rope dodder

NatureServe

NNR - Unranked

SNR - Unranked

Minnesota

not listed

Weed Status

FN – Federal noxious weed

RS – State restricted weed seed

Nativity

Native

Occurrence

 

Habitat

Moist or wet. Prairies, sedge meadows, fens, roadside ditches, stream banks.

Hosts

Mostly plants in the family Asteraceae, including Sunflower (Helianthus), goldenrod (Solidago), and ironweed (Vernonia), but also milkweed (Asclepias) and possibly mountain mint (Pycnanthemum).

Flowering

July through September

 
Flower Color

White

 
Height

 

 

Identification

This is an annual herbaceous vine that parasitizes the above-ground portion of other plants. In the spring a seed produces a single, slender, fast-growing stem, and a single root. The root is for anchoring only. It does not absorb nutrients and withers away after the stem attaches to a host plant. The stem lives solely on the nutrients stored in the embryo. It must find and attach to a host plant in 5 to 10 days or it will die. It seeks a compatible host by detecting and growing toward specific airborne volatile organic compounds. When it encounters another plant it wraps around it. If the plant is a suitable host the dodder stem will produce sucker-like, specialized roots (haustoria) that penetrate and draw nutrients from the host plant’s tissue. As it continues to grow it becomes more robust and climbs the host, twining in a counter-clockwise spiral.

The stems are wiry, branched, hairless, and yellowish-green, yellow, or orange. They are medium in diameter relative to other dodders but vary greatly in width, even on the same plant. They are mostly 1 64 to 3 128 (.4 to .6 mm) but may be up to 1 16 (2 mm) in diameter. The stem sections between flower masses wither and fall away, often by flowering time.

The leaves are alternate, stalkless, scale-like, and 1 32 to long. There is usually a single leaf subtending each node.

From May to early July rope dodder looks like orange tangled string. In July it produces flowers on parts of the stem that are tightly appressed. The inflorescence is a dense, rope-like mass of tiny flowers wound spirally around the stem of the host. The flowers are arranged in two parallel rows on opposite sides of the stem.

Each flower is subtended by several overlapping modified leaves (bracts). These floral bracts are yellowish at first, lance-shaped, and completely enclose the nascent flower. They are sharply pointed, boat-shaped, and bent backward and downward at the tip. After a few weeks the bracts turn white, the stem withers and falls away between inflorescences, and the flowers emerge above the bracts.

The flowers are stalkless and to 3 16 long. They contain both male and female reproductive parts (perfect). They have 5 sepals, 5 petals, 5 stamens, and 2 styles. The sepals and petals are smooth, not hairy or bumpy. The sepals (calyx) are white and similar to the floral bracts but distinct, not fused together; sharply or bluntly pointed at the tip; and somewhat spreading at the tip but not bent backward. The petals are white, united at the base into a cylindrical corolla tube, and separated at the tip into 5 lobes. The lobes are shorter than the corolla tube, oblong to lance-shaped, sharply or bluntly pointed at the tip, and spreading or sometimes bent backward. The stamens are attached to the corolla tube below the lobes and are shorter than the lobes. They have white filaments and yellow anthers. Below each stamen a scale-like appendage (infrastaminal scale) is attached to the corolla tube. The infrastaminal scale is narrowly oval and densely fringed on the margin, profusely fringed at the top, less so along the sides. It is shorter than the corolla tube reaches the base of the filament. The anthers are about as long as or shorter than the filaments. The styles are slender; 3 64 to long; distinct, not fused together; the same thickness throughout; and as long or longer than the ovary. At the tip of each style there is a head-like stigma. The stigma is not longer than thick.

The fruit is a flattened, globe-shaped, about thick capsule that may be more or less pointed at one end. It has paper-thin walls, a thickened collar and withered remnants of the corolla at the tip, and dried sepals at the base. When ripe it breaks open irregularly, not on a transverse circular line.

The seeds are light brown, oval, and 1 16 to 5 64long.

 
Similar
Species

The dense rope-like inflorescence distinguishes this from all other dodders.


Distribution Distribution Map  

Sources: 2, 3, 4, 5, 7, 28.


Comments

Status
Rope dodder is considered a noxious weed in the United States and a restricted weed seed in Minnesota, but is listed as threatened in Florida and is a Special Concern species in Wisconsin.

 
Links

There are excellent microscopic photos of the tiny flowers at Iowa Plants.


Taxonomy

Family:

Convolvulaceae (morning-glory)

 

Tribe:

Cuscuteae (dodders)

 
Synonyms

 

 
Common
Names

cluster dodder

clustered dodder

rope dodder

   

 

 

 

 

 

 

 

 

 

 

Glossary

bract

Modified leaf at the base of a flower stalk or flower cluster.

 

calyx

The group of outer floral leaves (sepals) below the petals, occasionally forming a tube.

 

corolla

A collective name for all of the petals of a flower.

 

filament

On plants: The thread-like stalk of a stamen which supports the anther. On Lepidoptera: One of a pair of long, thin, fleshy extensions extending from the thorax, and sometimes also from the abdomen, of a caterpillar.

 

haustorium

In parasitic plants: a slender, root-like projection by which the plant connects to and obtains nutrients from tissue of the host plant. In fungi: specialized hyphae that penetrate and obtain nutrients from cells of a host. Plural: haustoria.

 

perfect

Referring to a flower that has both male and female reproductive organs.

 

scale

In plants, a small, usually flat and thin, modified leaf resembling the scale of a fish.

 

sepal

An outer floral leaf, usually green but sometimes colored, at the base of a flower.

 

stigma

In plants, the portion of the female part of the flower that is receptive to pollen. In Lepidoptera, an area of specialized scent scales on the forewing of some skippers, hairstreaks, and moths. In Odonata, a thickened, dark or opaque cell near the tip of the wing on the leading edge.

 

twining

Growing in a spiral usually around a stem of another plant that serves as support.

       

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  Parasite Dodder Time lapse Parasitic Plants
francischeefilms
 
   
 
About

Published on Feb 27, 2015

Parasitic plants Dodder. Not all plants contain chlorophyll or possess leaves or even roots. There are always the exceptions to be found in the natural world. Dodder is such a parasitic plant. Able to obtain all of its food in order to reproduce, without the aid of doing anything other than sucking the life out of it's host, another plant.

Like some crazy Sci Fi movie, the Dodder parasite merges with it's host where the Dodder's tissues are almost indistinguishable from the host tissue except for that trained eye.The only real plant like thing about Dodder is it's capacity to flower like normal flowering plants hence producing seed for the next generation.

The Dodder's seeds are special too, they tend to germinate in the height of Summer and not spring. The small seedlings are able to withstand almost desiccating conditions which would kill all but cacti. This capacity for survival really gives this parasitic plant an advantage.

Like many parasites, a common feature is that it doesn't kill its host but merely weakens it. Seed is almost microscopic and can be transported thousands of miles via unwary human or animal vectors.

Although the Dodder can infect numerous plants from the smallest of small to entire trees in some instances, not all plants are susceptible. Plants can resist it's attack by producing compounds known as phytoalexins.

Numerous species of Dodder are known.

 
     
  NATURE | Dodder Vine Sniffs Out Its Prey | What Plants Talk About | PBS
PBS
 
   
 
About

Published on Mar 18, 2013

Watch the full-length episode at http://video.pbs.org/video/2338524490/ (US Only) Unable to produce its own food, the dodder vine must live entirely off a host plant. In a series of experiments, Researchers Consuelo M. De Moraes and Mark Mesker show that to find a host plant from which to drain nutrients, the parasitic plant "sniffs" out the chemical scents released by the leaves of nearby plants. "What Plants Talk About" premieres April 3 at 8/7c (check local listings). http://www.pbs.org/wnet/nature/episodes/what-plants-talk-about/preview/8228/

 
     
  Planta parasita - Cuscuta sp.
Antolinbast
 
   
 
About

Uploaded on May 12, 2011

Fragmento de la serie "La vida privada de las plantas" donde se muestra el crecimiento de la "Cuscuta europaea".

 
     

 

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