Most species of Lonicera are hardy twining climbers, with a minority of shrubby habit a handful of species (including Lonicera hildebrandiana from the Himalayan foothills and L. etrusca from the Mediterranean) are tender and can only be grown outside in subtropical zones. The leaves are opposite, simple oval, 1 cm long most are deciduous but some are evergreen. Many of the species have sweetly scented, bilaterally symmetrical flowers that produce a sweet, edible nectar, and most flowers are borne in clusters of two (leading to the common name of "twinberry" for certain North American species). Both shrubby and vining sorts have strongly fibrous stems which have been used for binding and textiles. The fruit is a red, blue or black spherical or elongated berry containing several seeds in most species the berries are mildly poisonous, but in a few (notably Lonicera caerulea) they are edible and grown for home use and commerce. Most honeysuckle berries are attractive to wildlife, which has led to species such as L. japonica and L. maackii spreading invasively outside of their home ranges. Many species of Lonicera are eaten by the larvae of some Lepidoptera species—see a list of Lepidoptera that feed on honeysuckles.