blue toadflax

(Nuttallanthus canadensis)

Conservation Status
blue toadflax
Photo by Nancy Falkum
  IUCN Red List

not listed

     
  NatureServe

N5 - Secure

S3 - Vulnerable

     
  Minnesota

Special Concern

     
           
           
           
           
           
           
 
Description
 
 

Blue toadflax is an early season prairie wildflower. It is native to North America, Mexico, and western and southern South America. It is sometimes cultivated as an ornamental. It was introduced and is naturalized in Japan, North and South Korea, eastern Russian Federation, and the Indian subcontinent. In the United States it is common in the south and on the East Coast. It is uncommon in the southeast and metro regions of Minnesota, where it is at the northwestern extent of its range, and it is absent from the remainder of the state. It is found in prairies, old fields, roadsides, and disturbed sites. It grows under full sun in dry, sandy soil.

Blue toadflax is an annual forb that rises on two kinds of stems from a small taproot. First to appear is a radiating cluster (rosette) of a few to several vegetative stems. Vegetative stems are to 2 long (1 to 6 cm) long, hairless, and usually unbranched. They usually lay flat on the ground (prostrate), sometimes with just their tips ascending (decumbent). Some may eventually reach 4 (10 cm) in length with age. Later, one to four flowering stems emerge. Flowering stems can be 4¼ to 27½ (11 to 70 cm) tall but are usually no more than 20 (50 cm) in height. They are usually erect, but sometimes curve upward very near the base (strongly ascending), and are usually unbranched, but sometimes have a few branches near the tip. They are hairless below the inflorescence. Both kinds of stems are slender, round, and green to reddish-green. Vegetative stems are often withered or absent at flowering time.

Leaves on vegetative stems are opposite or in whorls of three, 116 to ½ (2 to 12 mm) long, and 164 to (0.5 to 3.0 mm) wide. They may be stalkless or on short leaf stalks. The leaf blades are narrow and inversely egg-shaped or elliptic. Leaves on flowering stems are alternate, unstalked, 316 to 1 (5 to 43 mm) long, and 164 to 116 (0.5 to 2.2 mm) wide. The leaf blades are linear or thread-like. Leaves of both kinds of stems are unlobed, hairless, and untoothed.

The inflorescence is a slender, up to 7 (18 cm) long, unbranched arrangement (raceme) of flowers at the end of the flowering stem. The flowers are widely spaced on the raceme, even at the start of flowering time. Each flower is on a 132 to ¼ (1 to 7 mm) long, erect or strongly ascending stalk (pedicel). At the base of the pedicel there is a single 132 to ¼ (1 to 7 mm) long, linear, bluntly pointed, modified leaf (bract).

The flowers have both male and female reproductive parts (perfect). They bloom from mid-May to mid-June. Each flower is 516 to ½ (8 to 13 mm) long including the spur. There are 5 outer floral leaves (sepals), 5 petals, 4 stamens, and 1 style. The sepals, together referred to as the calyx, are united at the base then separated into 5 narrow, sharply pointed, 116to (2.1 to 3.5 mm) long lobes. They are green to purplish-green and sometimes hairless but more often glandular-hairy toward the base. The petals, together the corolla, are light blue to light purplish-blue. They are united at the base then separated into two unequal lips. The upper lip is 132 to 116 (1.2 to 2.0 mm) long, sometimes a little longer, and divided into two equal lobes. The lobes are erect or slightly angled backward. The lower lip is 116 to ¼ (2 to 5 mm) long and is divided into three rounded, spreading lobes. The base of the lower lip is white and strongly arched. A nectar spur extends backward from the throat of the corolla. The spur is 116 to ¼ (2 to 7 mm) long and may be straight or curved. The stamens are arranged as two pairs of unequal lengths. The stalks (filaments) are hairless. The style has an unlobed, cap-like stigma.

The fruit is a (2.6 to 3.9 mm) long, (2.6 to 3.3 mm) wide, oblong egg-shaped capsule with 100 to 200 seeds.

 
     
 

Height

 
 

4¼ to 27½ (11 to 70 cm)

 
     
 

Flower Color

 
 

Light blue to light purplish-blue and white

 
     
 

Similar Species

 
  Kalm’s lobelia (Lobelia kalmii) basal leaves are spatula-shaped. It occurs in wet areas.  
     
 
Habitat
 
 

Dry. Prairies, old fields, roadsides, and disturbed sites. Full sun. Sandy soil.

 
     
 
Biology
 
 

Flowering

 
 

Mid-May to mid-June

 
     
 

Pests and Diseases

 
 

 

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 6, 24, 28, 29, 30.

 
  6/17/2022      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Uncommon in Minnesota

 
         
 
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 Asteranae  
 

Order

Lamiales (mints, plantains, olives, and allies)  
 

Family

Plantaginaceae (plantain)  
  Tribe Antirrhineae  
 

Genus

Nuttallanthus (toadflax)  
       
 

This species was formerly classified as Linaria canadensis. This and three other Linaria species were transferred to the new genus Nuttallanthus in 1988 based on characteristics of the flowers and the seeds.

 
       
 

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Linaria canadensis

 
       
 

Common Names

 
 

blue toadflax

Canada toadflax

oldfield toadflax

oldfield-toadflax

old-field toadflax

toadflax

 

 

 

 

 

 

 

 

 

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.

 

Decumbent

Reclining on the ground but with the tip ascending.

 

Elliptic

Narrowly oval, broadest at the middle, narrower at both ends, with the ends being equal.

 

Filament

On plants: The thread-like stalk of a stamen which supports the anther. On Lepidoptera: One of a pair of long, thin, fleshy extensions extending from the thorax, and sometimes also from the abdomen, of a caterpillar.

 

Glandular hairs

Hairs spread over aerial vegetation that secrete essential oils. The oils act to protect against herbivores and pathogens or, when on a flower part, attract pollinators. The hairs have a sticky or oily feel.

 

Linear

Long, straight, and narrow, with more or less parallel sides, like a blade of grass.

 

Pedicel

On plants: the stalk of a single flower in a cluster of flowers. On insects: the second segment of the antenna. On Hymenoptera and Araneae: the narrow stalk connecting the thorax to the abdomen: the preferred term is petiole.

 

Prostrate

Laying flat on the ground.

 

Raceme

An unbranched, elongated inflorescence with stalked flowers. The flowers mature from the bottom up.

 

Rosette

A radiating group or cluster of leaves usually on or close to the ground.

 

Sepal

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

 

Spur

On flowers: a hollow tubular appendage, often containing nectar, formed from a sepal or petal. On branches: a short shoot bearing leaves or flowers and fruit.

 

 

 

 

 
 
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Nancy Falkum

 
    blue toadflax      
           
 
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Other Videos
 
  Nuttallanthus canadensis, the blue toadflax. 3 Minutes plants. Simple flower/plants movie. 3分間の植物動画
ethnobotaist isamimasi
 
   
 
About

May 6, 2020

Simple plants movie. I love watching plants movie when I do exercise or mindfulness. All movies have 3 minutes long, and you can use it as a timer for cooking, exercise , relaxation or waiting for instant noodle. Hope you enjoy it.

3分間の植物動画です。個人的にはタイマーがわりに使っています。植物を見ながら運動したり、ラーメンの出来上がりをまったり、マインドフルネスをしたり、人をまったりしてします。植物で隙間時間を埋めると、人生がちょっとだけ豊かになるような気がしています。個人的な趣味の世界ですが、楽しんでいただけると幸いです。

 

 

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  Nancy Falkum
5/27/2022

Location: Kellogg Weaver Dunes SNA, Weaver Dunes Unit

 

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Created: 6/17/2022

Last Updated:

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