This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
There are two Dodders indigenous to this country, and we have the misfortune to have introduced a third with flax-seed from abroad. The one figured is the Greater Dodder, which is usually found clinging in a tangle round the stems of nettles, oats, thistles, vetches, etc. This close embrace is sinister in character, for, as may be guessed from the entire absence of leaves and green-colouring matter, the plant is a parasite. Its stem is a mere thread, varying from red to yellow in hue, and having at frequent intervals bunches of reddish flowers. These are very small, but if separated will be found to consist of a four - or five-parted calyx, a persistent pitcher-shaped corolla of similar parts, and stamens to match. Styles two, entirely within the flower. This species is not found north of Yorkshire, and is everywhere rare. It flowers from July to September. The common species, to be found growing on thyme, heather, and furze, is, The Lesser Dodder (C. epithymum), with finer stems of a more crimson tint, and the styles protruding. There is a variety of this which confines its attention to the clover plant, and has, in consequence, been raised to the dignity of a separate species by some authors (C. trifolii). In addition there is the Flax-dodder (C. epilinum), previously alluded to as having been introduced from the Continent with flax-seed.
Owing to the serious nature of the attacks of this foreign invader upon our flax-crops Professor Buckman was induced years ago to experiment, with the object of elucidating its mode of growth. He found that seeds of Dodder sown strictly apart from any host-plants germinated in four days, and on the sixth a thread-like plant was seeking a foster-parent, but by the eighth, not having succeeded in its object, it died. Others were sown in company with flax-seed, and in a few days the young dodders attached themselves to the young flax-plants, made one or two tight coils round the victims, whose growth soon lifted the dodders right out of the soil and thereupon the parasites sent aerial roots into the flax, and their natural roots dwindled and perished. Thereafter its true parasitical growth is most rapid, to the detriment of the foster plant.
- Convolulaceae -
The genus is included in the Natural Order Convolvulaceae.