white vervain

(Verbena urticifolia var. urticifolia)

               
Conservation Status

IUCN Red List

not yet assessed

white vervain (var. urticifolia)

NatureServe

NNR - Unranked

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FAC - Facultative

Midwest

FAC - Facultative

Northcentral & Northeast

FAC - Facultative

Nativity

Native

Occurrence

Common

Habitat

Moist to moderately moist. Woodland borders and openings, thickets, power lines, trails, disturbed sites. Partial sun.

Flowering

June to October

     
Flower Color

White

     
Height

20 to 60

     

Identification

This is an annual, biennial, or short-lived perennial forb. It rises on a single stem.

The stems are erect, slender, 20 to 60 tall, moderately to strongly four-angled, and usually branched near the base. They are moderately to densely covered with spreading, straight or somewhat curved hairs.

The leaves are opposite and broadly lance-shaped to oblong egg-shaped. They are mostly2 to 4¾ long and ¾ to 2¾ wide, but larger leaves may be up to 8 long and 4¾ wide. They are on ½ to 2 long leaf stalks (petioles) that are usually winged above the middle. The blades are unlobed, rounded or short tapered at the base, and tapered to a sharp point at the tip. They do not clasp the stem. The lower surface is hairless or moderately covered with whitish, 132 to 1 16long, coarse, stiff hairs. The margins are somewhat coarsely and sometimes doubly toothed.

The inflorescence is a very loosely spreading branched cluster (panicle) of several to numerous spikes at the end of the stem and additional smaller panicles or spikes rising from the upper leaf axils. The spikes are slender, usually stiffly ascending, and 3 to 20 long. At first they are relatively short and crowded with buds. As the flowers bloom from the base toward the tip the spike becomes greatly elongated. Only a few flowers on each spike are in bloom at any one time. The blooming flowers do not overlap.

The flowers are about wide. There are 5 sepals, 5 petals, 4 stamens, and 1 style. The sepals are green, and are united at the base into a narrowly bell-shaped tube (calyx), then separated into 5 short teeth that are unequal in length. The calyx is 1 32 to 1 16 long when in flower, elongating to about 3 16 long in fruit. It is covered with short, sharp, stiff, appressed hairs. The modified leaves (bracts) at the base of each flower are egg-shaped to narrowly egg-shaped and 164 to 1 16long. They are shorter than the calyx. The petals are white and 1 16 to long. They are fused at the base into a slender, funnel-shaped tube then separated into 5 blunt, broadly triangular limbs.

Each flower produces a cluster of 4 nutlets that are enclosed in the persistent calyx but are exposed at the tip. Each nutlet is narrowly ellipse-shaped, 5 64 long, and corrugated or ribbed on the back.

 
Similar
Species

White vervain (Verbena urticifolia var. leiocarpa) leaf underside is densely velvety, covered with 164 long hairs. The calyx is covered with soft, minute hairs that are barely visible without magnification. The nutlet is slightly shorter and smooth on the back.


Distribution Distribution Map  

Sources: 7.


Comments

Photography
This plant is difficult to photograph in its entirety. The flower spikes spread widely in all directions and the individual flowers are tiny. The inflorescence tends to get lost against the background and most of it is inevitably out of focus.


Taxonomy

Family:

Verbenaceae (verbena)

 

Subfamily:

Verbeneae

 

Genus:

Verbena (vervain)

 

Section:

Verbena

 

Series:

Leptostachyae

 
Parent

white vervain (Verbena urticifolia)

 
Synonyms

Verbena urticifolia var. incarnata

Verbena urticifolia var. simplex

 
Common
Names

burvine

nettle-leaf vervain

white verbena

white vervain

   

 

 

 

 

 

 

 

 

 

 

Glossary

axil

The upper angle where a branch, stem, leaf stalk, or vein diverges.

 

calyx

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

 

panicle

A pyramidal inflorescence with a main stem and branches. Flowers on the lower, longer branches mature earlier than those on the shorter, upper ones.

 

petiole

The stalk of a leaf blade or compound leaf that attaches the leaf blade to the stem.

 

sepal

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

       

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  white vervain (var. urticifolia)    
       

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  white vervain (var. urticifolia)    
       
       

 

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