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.
The hardy species are annual or perennial herbs, often woody at the base. Leaves opposite or scattered. Inflorescence terminal, umbellate or panicled. Flowers involucrate, several male and one female in each head. Perianth none, but represented by the involucral lobes, the latter having thick often viscid glands in the sinuses. Male flower consisting 'of a solitary stamen on a jointed stalk. Female flower naked, on an elongating stalk; capsule 3-lobed, 3-celled, each cell containing a solitary pendulous seed. This is a vast genus, comprising 700 species of widely different habit and aspect, occurring in all regions except the coldest. The name is the same applied by the ancient Greeks to some of the species.
3- or 4-rayed; involucral bracts large, cordate. Capsule smooth. A native of the South of Europe, and naturalised in some parts of Britain.
2. E. Cyparissias. - This is a dwarfer denser perennial species with sessile glaucous linear entire leaves and many-rayed terminal umbels. Bracts cordate, obtuse. Capsule granulate. A European species occurring as an introduced plant in Britain. .
E. amygdaloides is the tall perennial species so abundant in copses in the South of England; and E. Helioscopia is the common annual species.