Many of the parasitic plants are of microscopic dimensions, and others are larger species belonging to the Fungi or Mushroom group. Some, however, are flowering plants, and these only fall within the scope of our work. We shall first deal with parasites which have no green leaves or chlorophyll, and are therefore entirely dependent on outside sources for their supply of organic material, starting with the interesting Dodders (_Cuscuta_), which coil themselves round herbs, shrubs, or even trees, and produce sucking organs on their stems that come in contact with their host. These are all smooth plants, with globular clusters of yellowish-pink flowers, the calyx being of the same colour as the corolla. The former is deeply divided into four or five parts, and the corolla has four or five spreading lobes with as many scales inside its broad tube. The ovary has two distinct styles, and the fruit is a globular capsule. The following summary of distinguishing features will enable the reader to identify the British species of the genus:-- 1. The Greater Dodder (_Cuscuta europæa_).--A plant of a greenish yellow colour, generally more or less tinged with red, with flowers in sessile, globular clusters nearly half an inch in diameter, each individual flower being about a tenth of an inch. This species is not abundant. It may be met with in hop-fields, and is also parasitic on nettles, various shrubs, and trees, including the elder and the ash. 2. The Flax Dodder (_C. Epilinum_).--Very much like _C. europæa_, but the flowers are fewer in number, larger, and more fleshy. The calyx is nearly as long as the corolla, with sharply-pointed segments; and the corolla tube is always globular. This species is not indigenous, but is sometimes met with in flax-fields. 3. The Lesser Dodder (_C. Epithymum_).--A more slender plant, with thread-like stems, and flowers in small, compact, globular heads, with red calyx and cylindrical corolla. This species occurs principally on sunny heaths, where it is parasitic on shrubby plants, such as thyme and ling. It is much more common than the foregoing. 4. The Clover Dodder (_C. Trifolii_).--Very much like the Lesser Dodder, of which it is sometimes regarded as a variety. Its calyx is of a very pale colour, and is almost as long as the tube of the corolla, which is cylindrical in form. It is rare, but sometimes appears in undesirable numbers in clover fields. All the species produce their flowers in August and September, but _C. europæa_ may often be seen in bloom very early in July.