Anyone peeking inside a wildflower guide now and again may have noticed that aside from the near-impenetrability of the Latin binomial nomenclature (Latin names to you and me), there is a certain repetition in the species names used. This repetition is really useful to understand the ecology of the plant in question and with a bit of practice can slip off the tongue as naturally as the English common name.
For example, 'repens' means 'creeping'. Thus, a creeping buttercup is Ranunculus repens and white clover, which has a creeping growing habit, is Trifolium repens. The word 'reptans' also means 'creeping', as in Ranunculus reptans (creeping spearwort) and Potentilla reptans (creeping cinquefoil). Nigrum means 'black', so Centaurea nigra (black knapweed), Sambucus nigra (elder) and Solanum nigrum (black nightshade) have fairly intuitive descriptions.
The root word pratensis (or variant pratense) means 'meadow', and gives a clue as to the habitat in which one might find red clover (Trifolium pratense) or the meadow crane's bill (Geranium pratense). Similarly, 'arvensis' means 'in the field', and so Viola arvensis (field pansy) and Cerastium arvense (field mouse-ear) are easy to remember. Vulgaris means 'common', as in Linaria vulgaris (common toadflax). Silvestris means 'of the wood' and so Geranium sylvaticum refers to wood crane's bill; Myosotis sylvatica is commonly known as wood forget-me-not, and Stachys sylvatica is the binomial for hedge woundwort, which is usually found in woodlands. A word of warning though – get up close to the leaves at your peril: this is a seriously stinky plant!