Northern Ontario Plant Database

Plant Description

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Lonicera dioica L.

En: limber honeysuckle, smooth honeysuckle, glaucous honeysuckle
Fr: chèvrefeuille dioïque

Caprifoliaceae (Honeysuckle Family)

General: A perennial, trailing or climbing, woody vine to 3+ m long. Young stems have a waxy, bluish-white (glaucous) coating; older woody stems brown or grayish, with shredding bark.

Leaves: Opposite, simple, pinnately-veined, sessile to petiolate (to 1 cm long) in lower leaves, deciduous. The upper 1–4 pairs of opposite leaves with fused bases (connate-perfoliate), the uppermost pair further modified into a rhombic or elliptic disk that subtends the inflorescence. Leaf blades oblong, ovate, or obovate, 4–12 cm long, 1–6 cm wide; upper surface green, smooth (glabrous); lower leaf surface pale and glaucous, usually glabrous; leaf base tapering (cuneate); apex blunt (obtuse) to rounded; margins entire.

Flowers: Bisexual, in a terminal stalked cluster (spike) of 1–3 whorls of several flowers, subtended by a rhombic or elliptic, connate-perfoliate disk with indented (retuse) to pointed (acute) tips, or abruptly ending in a short, sharp point (mucronate). Calyx minute; corolla greenish-yellow to orange or purplish-red, 1.5 to about 2 cm long, tubular, with a gibbous bulge near the base, ending in 5 oblong lobes arranged in a bilabiate manner, with 3 lobes fused into an upper lip and 2 fused into a lower lip; stamens 5, attached to the inside of the corolla base (epipetalous), filaments hairy toward the base; the single pistil has an inferior ovary and a long-exserted style with a capitate stigma. The outer surface of the corolla and ovary are glabrous. Flowers bloom in early summer.

Fruit: Smooth, orange to red, ovoid berries, sessile, arranged in terminal whorls and subtended by the connate-perfoliate disk. Fruits mature in late summer to autumn.

Habitat and Range: A variety of dry to moist habitats, including open woods, slopes, rocky shores, thickets, and clearings; often in calcareous areas. The glaucous honeysuckle is native to northeastern and central North America. In Ontario, it occurs as far north as the Upper Severn River basin (Soper & Heimburger 1982).

Internet images: The Lonicera dioica webpage from the Connecticut Botanical Society.

The Lonicera dioica webpage from the Robert W. Freckmann Herbarium, Univ. of Wisconsin - Stevens Point.

Similar Species: The only other climbing honeysuckle native to Ontario is Lonicera hirsuta, the hairy honeysuckle, which has somewhat hairy leaves with ciliate margins. Blades of only the upper 1-2 pairs of opposite leaves are connate-perfoliate, with the upper pair modified into a concave disk that subtends the inflorescence. The young stems and lower leaf surfaces of Lonicera hirsuta lack the glaucous coating typical of stems and leaves of Lonicera dioica.

Lonicera chart I: Native climbing or trailing vines with terminal whorls of flowers and fruits

traits	Lonicera hirsuta (hairy honeysuckle)	Lonicera dioica (glaucous honeysuckle)
leaf shape	broadly elliptic, oval, or ovate	narrowly elliptic to oblong
leaf surface	somewhat hairy on both surfaces	smooth, usually glaucous beneath
leaf apex	acute to blunt	blunt to rounded
leaf base	rounded or tapering, upper 1–2 leaves connate-perfoliate	tapering, upper 1–4 leaves connate-perfoliate
leaf margins	ciliate	entire
fruit	a cluster of orange to red, ovoid berries, subtended by a connate-perfoliate disk	a cluster of orange to red, ovoid berries, subtended by a connate-perfoliate disk

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