Lonicera dioica L.
Habitat: Rocky banks, dry woods and thickets. [Dry barrens (partly forested, upland); Hardwood to mixed forest (forest, upland); Forested wetland]
Range: Southern Maine and southwestern Quebec to Manitoba, south to Georgia and west to Missouri.
Aids to Identification: Lonicera dioica is a vining honeysuckle with opposite elliptic leaves which are distinctively whitened beneath. The top 1-4 pairs of leaves are joined at their bases, appearing like one leaf pierced by the stem. The flowers, which can be variously colored, have the typical "honeysuckle" shape, i.e. they are definitely two-lipped (compare the other native vining honeysuckle in Maine, L. sempervirens, which has five-petalled almost regular flowers; it too is rare here). The only other vining honeysuckle in Maine is Japanese honeysuckle, L. japonica. This species occasionally occurs in Maine and is common and pesty southward and differs in having egg-shaped rather than elliptic leaves which have a definite though short stalk at the base and paired flowers (the flowers of L. dioica are borne in threes).
Ecological characteristics: The mountain honeysuckle has not been observed in detail in Maine, so ecological relationships here are not well known.
Phenology: Flowers May to July; fruits July to September.
Synonyms: Lonicera dioica L. var. glaucescens (Rydb.) Butters; Lonicera glaucescens (Rydb.) Rydb.
Known Distribution in Maine: This rare plant has been documented from a total of 9 town(s) in the following county(ies): Cumberland, Kennebec, Sagadahoc, York.
Reason(s) for rarity: At northern limit of range; not rare south of Maine.
Conservation considerations: Some of the mountain honeysuckle's habitat may have been lost. This plant is restricted to statewide southern Maine, and known populations are vulnerable to conversion of their habitat to residential or commercial use. Such conversion is believed to be partly responsible for its rarity in Maine.