twinflower

(Linnaea borealis ssp. americana)

               
Conservation Status

IUCN Red List

not listed

twinflower

 

NatureServe

NNR - Unranked

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FACU - Facultative upland

Midwest

FAC - Facultative

Northcentral & Northeast

FAC - Facultative

Nativity

Native

Occurrence

Very common

Habitat

Moist or moderately moist. Deciduous, coniferous, and mixed forests and woodlands, thickets, cedar swamps, and bogs. Partial shade. Peat, rotting logs, and mossy boulders.

Flowering

Early mid-June to early August

 
Flower Color

Pink to white

 
Height

2 to 4

 
 
Identification

Twinflower is a perennial, ground-hugging, evergreen, dwarf shrub (subshrub). It occurs throughout Canada. In the United States it occurs in the east from Maine south to New York and west to Minnesota, and in the west from Washington east to Montana and south to northern California. In Minnesota it is very common in the northeast and north-central regions, uncommon in the metro and southeast regions, and absent from the south and southwest regions. There are a few occurrences in the north-western counties and only a single occurrence in Fillmore County along the South Branch Root River. Twinflower sometimes forms large colonies. It is found in deciduous, coniferous, and mixed forests and woodlands, thickets, cedar swamps, and bogs, in moist or moderately moist conditions. It grows under partial shade in peat and on rotting logs, and mossy boulders.

The stems are slender, 3 to 6 (1 to 2 m) long, and lie flat on the ground (prostrate). They are slightly woody, reddish-brown, and covered with short, fine hairs. Older stems are woody and 116to (2 to 4 mm) in diameter. Every few inches a branch rises from a node. Branches can be 2 to 6 tall but are usually no more than 4 in height. They are erect, slender, reddish-brown, leafy, and hairy. New roots are produced where a node touches the ground or other substrate. After many years the stem may separate there and a new plant is created.

The leaves are opposite, evergreen, somewhat leathery, to 1116 (9 to 18 mm) long, and ¼ to (7 to 15 mm) wide. They are on 116 to 316 (2 to 5 mm) long leaf stalks. The leaf blades are egg-shaped (widest below the middle), inversely egg-shaped (widest above the middle), or elliptical (widest at the middle), to almost circular. They are angled at the base and rounded at the tip. The upper surface is dark green and sparsely covered with fine hairs. The lower surface is pale green and hairless or almost hairless. The margins have 1 to 4 rounded teeth above the middle on each side. Smaller leaves are often untoothed.

The inflorescence is a pair of flowers at the end of an erect, 1 to 3 (3.5 to 8 cm) long, inflorescence stalk (peduncle). Each flower droops at the end of a short, less than long, flower stalk (pedicel). The peduncle and pedicel are covered with gland-tipped hairs. There is a small modified leave (bract) at the base of each pedicel.

Each flower is bell-shaped and 516 to ½ (8 to 12 mm) long. There are 5 outer floral leaves (sepals), 5 petals, 4 stamens, and 1 style. The ovary, at the base of each flower, has two pairs of modified leaves, an outer, large, shield-like pair, and an inner, minute pair. The ovary and outer bracts are covered with gland-tipped hairs. The sepals (together the calyx) are green, united at the base into a short tube then separated into 5, narrow, 116to (2 to 3 mm) long lobes. The sepals are covered with gland-tipped hairs. They fall off when the plant is in fruit. The petals (together the corolla) are pink at the base, white at the tip. They are united at the base for more than half of their length into a funnel-shaped tube then separated into 5 pointed lobes. The inner surface of the corolla is densely covered with long hairs. The outer surface is hairless. The stamens are short and do not protrude from the corolla tube. The style has a slender white stalk and a cap-like stigma. It protrudes beyond the corolla tube.

The fruit is a yellow, dry, globe-shaped, 116 (2 mm) in diameter capsule with 1 seed. The fruit droops at the end of the pedicel and is enclosed by the persistent outer bracts.

 
Similar
Species

 

 
Distribution Distribution Map  

Sources: 2, 3, 4, 5, 7, 8, 24, 28, 29, 30.

 
Comments

 

 
Taxonomy

Family:

Linnaeaceae

 

Subfamily:

Linnaeoideae

 

Genus:

Linnaea (twinflower)

   
 

The Eurasian subspecies of twinflower is Linnaea borealis ssp. borealis. In North America, L. b. ssp. longiflora occurs in the west, including Alaska, L. b. ssp. americana occurs in the east, including Minnesota. Some authors do not recognize L. b. ssp. americana, and treat all North American plants as L. b. ssp. longiflora.

 
Synonyms

 

 
Common
Names

American twinflower

twinflower

   

 

 

 

 

 

 

 

 

 

Glossary

Bract

Modified leaf at the base of a flower stalk or flower cluster.

 

Calyx

The group of outer floral leaves (sepals) below the petals, occasionally forming a tube. Plural: calyces.

 

Corolla

A collective name for all of the petals of a flower.

 

Node

The smal l swelling of the stem from which one or more leaves, branches, or buds originate.

 

Pedicel

In plants: the stalk of a single flower in a cluster of flowers. In Hymenoptera and Araneae: the narrow stalk connecting the thorax to the abdomen.

 

Peduncle

In angiosperms, the stalk of a single flower or a flower cluster; in club mosses, the stalk of a strobilus or a group of strobili.

 

Prostrate

Laying flat on the ground.

 

Sepal

An outer floral leaf, usually green but sometimes colored, at the base of a flower.

       
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Luciearl
       
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Luciearl
9/30/2020

Location: Cass County

twinflower


     
     
 
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Created: 11/2/2020

Last Updated:

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