This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Herbs with quadrangular stems and whorled entire leaves. Flowers very small, articulated with the pedicel, in axillary or terminal stalked cymes. Calyx-limb superior, annular, or toothed, or obsolete. Corolla rotate, campanulate or funnel-shaped; lobes valvate. Stamens 3 to 5, inserted on the corolla-tube. Fruit didymous, of two 1-seeded lobes. The species are numerous in temperate countries. Our native Groose-grass, or Cleavers, and Bedstraw (Galium spp.) belong to this sub-order.