The bedstraws are slender, sprawling herbs that have square stems (in cross-section) and they belong to the genus GALIUM. This genus belongs to the family RUBIACEAE, which includes the Gardenias, Coffea (for coffee) and Cinchona (bark yields quinine = Jesuits' bark).
Galium odoratum (sweet woodruff) is a woodland bedstraw, which tends to form 'a carpet' and is a perennial. Galium aparine ( aka goosegrass, kisses, cleavers, sticky bobs, sticky willy, sweethearts and robin run the hedge) is more common and is a 'scrambler"; it is also an annual.
Stems of cleavers spread and sprawl across the ground or up and over other plants / shrubs, using these to help form a dense network of stems and leaves up to a height of 4 - 5 feet . This network can shade out other species beneath them, reducing competition for water and other nutrients. Cleavers is common in hedges, arable fields and gardens. The leaves are simple, and arranged around the stems in whorls (of 6 to 8). Both the stems and leaves of cleavers have many, minute hooks or barbs which help the plant to scramble over others - see adjacent photograph.
Flowers, which form in June through to August, arise in the leaf nodes. They are small and white, with four petals joined at the base and when pollinated will form small, spherical fruits which like the stems and leaves bear many small hooks.
The fruits tend to occur in pairs, and a single plant may produce thousands in a lifetime. The seeds when dried and lightly roasted are said to give a coffee-like drink.
Some Galium species, such G. verum (lady's bedstraw) and G.odoratum (sweet woodruff, which has the largest leaves of the bedstraw family) are rich in a chemical - asperuloside, which gives a scent like that of newly mown hay or vanilla. Their dried leaves may be used in pot pourri or in former times for the packing of linen and in mattresses - hence the name bedstraw. The chemical is not dis-similar to the prostaglandins and hence the herb is of interest to the pharmaceutical industry. Sweet woodruff has larger flowers and broader leaves than other bedstraws.
The bedstraws are sometimes used by herbalists and can also be used to make a red dye.