hairy four o’clock

(Mirabilis albida)

               
Conservation Status

IUCN Red List

not yet assessed

hairy four o’clock

NatureServe

N5 - Secure

SNR - Unranked

Minnesota

not listed

Nativity

Native

Occurrence

 

Habitat

Dry. Prairies, hills, disturbed sites. Full sun.

Flowering

May to August

Flower Color

Pale pink

Height

8 to 40


Identification

This is an erect perennial rising from a thick, dark, fleshy or woody, taproot.

The stems are hairy, especially near the nodes. They are usually erect, but they may recline on the ground with the tips ascending.

The leaves are opposite, untoothed, hairy, either lance-shaped or lance-egg–shaped, almost stalkless, and taper to the base. They are spreading or strongly ascending at a 10° to 90° angle. The upper leaf surface is green to grayish or bluish green. The principal leaves are to ¾ wide.

The inflorescence is single branched clusters at the end of each stem branch and in the leaf axils. The clusters appear at the end of to ½ long hairy stalks. The clusters have 3 flowers each and are themselves hairy.

The flowers are ¼ to ½ wide. They have little or no fragrance. There are 5 pale pink petal-like sepals. The sepals are fused at the base forming a tube, then flare outward. There are 5 hairy bracts, to ¼ long, at the base of the flower that are fused into a pale green, sometimes tinged with purple, narrowly to widely bell-shaped cup. The flowers open in the late afternoon, giving this plant its common name, remain open all night, and close in the morning.

The fruit is a one-seeded achene. It is subtended by the persistent, bell-shaped fused bracts that have increased in size as the fruit developed, becoming to ½ long.

 
Similar
Species

Heart-leaved four o’clock (Mirabilis nyctaginea) has a hairless, distinctly forked stem. The leaves are wider, often hairless, and on longer leaf stalks. The bract cups are hairless.

Narrow-leaved four o’clock (Mirabilis linearis) has linear leaves.


Distribution Distribution Map   Sources: 2, 3, 4, 5, 7, 28.

Comments

 


Taxonomy

Family:

Nyctaginaceae (four o’clock)

 

Tribe:

Nyctagineae

 
Synonyms

Allionia hirsuta

Mirabilis hirsuta

Oxybaphus hirsutus

 
Common
Names

hairy four o clock

hairy four oclock

hairy four-oclock

hairy umbrella-wort


 

 

 

 

 

 

Glossary

Achene

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.

 

Axil

The upper angle where the leaf stalk meets the stem.

 

Bracts

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

 

Linear

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

 

Sepal

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

       

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Inflorescence

  hairy four o’clock   hairy four o’clock
       

Flower

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Leaves

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Infructescence

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  Pale Umbrellawort (Mirabilis albida)
Bill Keim
 
  Pale Umbrellawort (Mirabilis albida)  

 

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