 Some 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, 1–10 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).