Leaves and Stem
Bugle is a perennial herb that produces long (leafy) runners that root.
The leaves at the base of the upright stem are often in the form of a rosette and are between 4 and 7 cm in length.
They are quite 'shiny' and roughly oval being broad in the middle and tapering off towards the tip of the leaf. Sometimes, the leaves are richly pigmented - being purple, brown and bronze in colour.
The stems are also quite coloured (red / purple), roughly square in cross section and bear numerous hairs (see image below) :
Flowers and Fruits
The flowers form on upright, coloured and hairy stems.
They are formed from petals that have fused together during their development to form a two lipped structure (see left hand image below).
The sepals too have joined together during their development to form a tube like structure. There are 5 'teeth' on this outer structure (see right hand image below).
Beneath the flower is a leaf-like structure or bract (also shown in the LH image below).
The flowers are a purple / blue colour - sometimes (though rarely) cream or pink.
Ecology and other notes
Bugle (Ajuga repens) belongs to the same family as deadnettles, yellow archangel and wound worts - the Lamiaceae, which were formerly known as the Labiates / Labiatae.
Richard Mabey in "Flora Britannica"says on names - the C14th name was wodebroun; bugle probable comes from the dark lustrous long glass beads once sewn into clothes as ornaments.