DIPANJAN GHOSH

The dodder is often blamed for the irreparable damage it causes to a large number of crop and garden ornamentals. But it has several Feature Article Feature benefits too. DESPICABLE DODDERS Also known as reflexa Roxb., circumnutation) until they latch on to the the dodder belongs to the family host, often in less than twenty four hours. Cuscutaceae. Earlier it had been Before a host is reached, the dodder classified as a member of relies on its cotyledons for food. Once the Convolvulaceae. In this sense, it is a close dodder seedling finds a host plant, it quickly T holds the distinction of being one of relative of Bridal Creeper, Morning Glory, wraps itself around the host’s stem. Dodder the seven deadliest weeds in Needle Creeper, and Sweet potato. The seedlings that fail to find a host die within Iexistence today, severely infesting Cuscuta includes many species ten days, although the exact time agricultural and horticultural crops. The (approximately 150 species), all of which depends on how humid the air is, and dodder is a parasitic look remarkably alike. They differ, however, probably the original seed size. immensely disliked by gardeners. This in their geographic distribution and also in At the time of germination, the new aggressive weed extensively holds on to their host preferences. dodder sprout has to reach a green plant bushes and hedges in dense interlacing quickly. The young stem grows towards masses. Struggle for Survival green light transmitted through nearby Since the dodder has no chlorophyll, The dodder can be identified by its thin leaves of the host plant. Recent researches its thin twining stem is occasionally stems that appear leafless, with the leaves have also revealed that certain volatile colourless. Yet some dodder plants are reduced to minute scales. It almost substances emitted by the host also help tinged with yellow or orange and resemble completely lacks chlorophyll, and is the dodder to seek a host plant alongside. cooked spaghetti. The dodder is most unable to photosynthesize effectively, often seen in marshes, roadsides, fields and being entirely dependent upon a plant Aggressive Parasite thickets throughout the tropics and sub- host for food, water, nutrients, and physical If the host plant contains food beneficial tropics. They become rare in cool support. That is why the dodder is obligately to the dodder, the dodder immediately temperate climates. parasitic in nature. However, it is said to produces haustoria, modified adventitious The dodder is known to Indians from contain some chlorophyll in the buds, fruits roots that eventually puncture through the time immemorial. In ancient Sanskrit verses, and stems, but the amount of food host stem. Haustoria begin as swellings it has been cited as ‘Akashballi’. In Hindi, it manufactured in these tissues is of little (known as prehaustoria) on the surface of is known as ‘Amar bel’. The dodder has significance to the survival of the plant. a coiled dodder stem. Once the host stem various English folk names such as ‘Devil’s The new dodder plant grows from surface has been breached, haustoria guts’, ‘Devil’s ringlet’, ‘Gold-thread’, seeds and sprouts from the ground like any make connection with host phloem tissues ‘Hailweed’, ‘Hairweed’, ‘Hellbine’, other plant. Upon emergence, the leafless (and sometimes also with host xylem), and ‘Lovevine’, ‘Strangleweed’, ‘Witches’ dodder seedlings begin counter- then proceed to extract carbohydrates, shoelaces’ and so on. clockwise twining (technically called water, and mineral salts. The original root 53 SCIENCE REPORTER, DECEMBER 2011 Feature Article

At the time of germination, the new dodder sprout has to reach a green plant quicklyquickly.. The young stem grows towards green light transmitted through nearby leaves of the host plant.

in the soil then dies and the parasite finally provided with a hard seed coat and are continuously, and may reach high into the loses its connection to the ground. produced in large quantities. canopy of shrubs and trees. In temperate The dodder can grow up to 3 inches Smoothseeded Alfalfa dodder [C. regions, the dodder is restricted to every day and continually produces new approximata Bab. var. urceolata (Kunze) relatively low vegetation that can be haustoria to drain the host plant of Yuncker] is reported to produce over reached by new seedlings each spring. nutrients. However, it rarely kills its host plant, 16,000 seeds per plant in a single season. Dodder parasitizes various kinds of although the host shows stunted growth Moist soil and sunlight is required for seed wild and cultivated plants. It attacks patterns after severe infection. germination. Dodder seeds can agricultural crops like cotton, flax, onion, The dodder has numerous tiny (2 to 4 germinate without a host plant, unlike the potatoes, etc., and is especially mm long), bell-shaped, white, pink, seeds of most parasitic plants. Yet in some destructive to fodders like alfalfa, clover, cream to yellowish flowers that can be cases, if no suitable host is present, the English ivy, etc. Ornamentals infested by borne in tight balls or in a loose cluster seed may remain dormant for years. The dodders include black locust, depending on the species. Flowers seed viability ranges up to sixty years and chrysanthemum, dahlia, helenium, normally appear from early June to the germination can also be delayed for petunia, trumpet-vine, and so on. end of October. Some species flower years. Moreover, spotted jewelweed and later, for instance, C. reflexa flowers from evergreen blackberry are usually October to January. After the flowers are Inflicting Damage considered to be good plants to have gone, small fruits appear. Dodder fruits are The dodder dominates all the possible around, because of their beauty, their fruit, small (about 2 to 3 mm wide) and have 1 terrestrial habitat conditions, from plain and their ability to attract wildlife. to 4 seeds inside. The skin of the fruit is lands to the hills. It may be a rural crop The dodder’s life span is a year long. paper-thin and breaks easily, spilling the field to an urban household garden, trees It dies when the weather gets cold. seeds on to the nearby area where they in and around an industrial installation, and Dodders cover winter in a unique fashion. can grow with plenty of host plants. even bushes along the railway tracks or Even after the death of the dodder plant The seeds are minute, yellow to the roadside avenue trees – the dodder in the winter, haustoria can stay alive inside brown or black in colour, nearly round and spreads elsewhere. The dodder can grow a host plant. When the weather gets warm have a fine rough surface with one round and attach itself to multiple plants. In again, they can grow new plants, already and two flat sides. These seeds are tropical areas it can grow more or less attached to a host. Besides, some species

SCIENCE REPORTER, DECEMBER 2011 54 Feature Article

The dodder is known to Indians from time immemorial. In ancient Sanskrit verses, it has been cited as ‘Akashballi’. In Hindi, it is known as ‘Amar bel’.

muscle pain, paralysis, flatulence and intestinal worms. The dodder can be particularly helpful in certain agricultural and horticultural practices. When it becomes a parasite of some weed plant such as clover, English elm phloem necrosis. In addition, phloem- ivy and wild onion, it helps to control the inhabiting rickettsia-like bacteria have luxuriant growth of these plants. Some fast- been found to be present in dodder. growing plant species like goldenrods, lizard’s tail, Virginia-creeper, etc., often Dodder Benefits crowd out other plants. The dodder The dodder is an efficient remedy for a checks the growth of these plants by large number of human diseases. Its stem parasitizing them. and seeds are employed to control many urinary, biliary and intestinal problems. All Managing Dodder the parts of a dodder plant are bitter in Its wide host range and the long life of its taste due to the presence of various dormant seeds make the dodder hard to organic components. It contains alkaloids control and nearly impossible to such as cuscutin and cuscutalin, flavonoids eradicate. The dodder produces large (including kaempferol and quercetin) and numbers of seeds that can be hydroxycinnamic acid. In addition, dodder disseminated by irrigation water, in the seeds contain wax (ester) and a pigment manures of livestock that have eaten amarbelin. However, a person suffering infested alfalfa, or along with the seed of from hemorrhoids should avoid using a crops that were infested with dodder. So, dodder-based herbal remedy. the dodder is best controlled by using Contemporary herbalists still consider clean seeds. Once the dodder becomes the dodder to be a valuable remedy for established, eradication is almost of dodders are host-specific. This means the treatment of specific disorders. The impossible. that a particular species of dodder only remedy made from the entire plant has Mechanical removal can be grows on a particular species of host plant. carminative and mild-diuretic properties. attempted, but once the dodder has However, most dodder species grow on It is also considered to stimulate the produced the haustoria, it is quite difficult several different types of plants, both appetite, prevent cough and cold, as well to avoid damage to the host plant. If the monocotyledonous and dicotyledonous. as enhance liver function. Besides, the dodder has germinated and has attached Dodder ranges in severity based on dodder is also known to possess a mildly to a host plant, removal of both is the its species and the species of the host, laxative effect when ingested. As a ultimate recommendation. Few crops such the time of attack, and whether any traditional medicine, the dodder is valued as cereals, corn, cowpeas, soybeans and viruses are also present in the host plant. in the functioning of gall bladder and liver velvet beans are resistant to dodder By enervating the host plant, the dodder ailments. attack and thus assist in biological control. decreases the ability of plants to resist viral A decoction prepared from the stem Certain herbicides are also effective diseases. The dodder can also spread of the dodder is employed in the against the dodder. plant diseases from one host to another if treatment of urinary problems, intermittent it is attached to more than one plant. It fever, traumatic pain, skin diseases and in Mr Dipanjan Ghosh is a postgraduate teacher in has been shown to spread the yellow wound healing. Stem decoction is also Biology. Address: Chotonilpur Pirtala, P.O.: Sripally, disease pear decline, aster yellows, helpful in treating sciatica, gout and Dist. Burdwan-713103, West Bengal; Email: tomato big bud, vinca virescence and jaundice. Seed extracts are used against [email protected] 55 SCIENCE REPORTER, DECEMBER 2011