twinflower

(Linnaea borealis ssp. americana)

Conservation Status
twinflower
 
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FACU - Facultative upland

     
  Midwest

FAC - Facultative

     
  Northcentral & Northeast

FAC - Facultative

     
           
 
Description
 
 

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.

 
     
 

Height

 
 

2 to 4

 
     
 

Flower Color

 
 

Pink to white

 
     
 

Similar Species

 
     
     
 
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.

 
     
 
Biology
 
 

Flowering

 
  Early mid-June to early August  
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

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

 
  10/31/2020      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Very common

 
         
 
Taxonomy
 
  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Rosanae  
 

Order

Dipsacales (honeysuckles, moschatels, and allies)  
 

Family

Caprifoliaceae (honeysuckle)  
  Subfamily Linnaeoideae  
 

Genus

Linnaea (twinflower)  
  Species Linnaea borealis (twinflower)  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

American twinflower

twinflower

 
       

 

 

 

 

 

 

 

 

Glossary

Bract

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

 

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

On plants: the stalk of a single flower in a cluster of flowers. On 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
       
  twinflower   twinflower
       
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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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