red maple

(Acer rubrum var. rubrum)

Conservation Status
red maple
 
  IUCN Red List

not listed

     
  NatureServe

N5 - Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FAC - Facultative

     
  Midwest

FAC - Facultative

     
  Northcentral & Northeast

FAC - Facultative

     
           
 
Description
 
 

Red Maple is a moderately fast-growing, moderately long-lived, medium to large, deciduous tree rising on a single trunk from shallow, horizontal roots. In Minnesota mature trees are usually 40 to 70 tall and up to 24 in diameter, though large individuals can reach over 80 in height. They typically live 100 years, rarely more than 150 years.

In the forest the trunk is usually unbranched for half its length and the crown is narrow and short. In the open the trunk usually divides near the ground into a few widely ascending branches and the crown is dense and long.

The branches are opposite, widely spreading, and ascending.

The bark on young trees is silvery gray and smooth with random, vertical cracks. If it is bruised or scraped it emits no odor. On mature trees the bark is gray to dark grayish-brown. It is separated into multiple layers of vertical, plate-like strips with scaly ridges. The strips are attached in the middle but loose and sometimes curling at the top and bottom.

The twigs are slender, shiny, bright red to reddish-brown, and hairless. When crushed they do not emit a rank odor. The sap of a freshly cut twig is clear. Opposite twigs appear in a V-shape on the branches. Younger twigs have obvious, small, white, pore-like openings (lenticels). At the end of the twig is a smooth, shiny, reddish, to ¼ long, blunt, terminal bud. It is composed of 2 to 5 pairs, but usually 4 pairs, of overlapping scales.

The buds are dark brown, egg-shaped to elliptic, ¼ long, and blunt at the tip. They are composed of 6 to 10 dark red overlapping scales. The terminal bud is red and relatively short. The leaf scar is have V-shaped and has 3 dots (bundle scars).

The leaves are opposite, stalked, 2½ to 4 long, and nearly as wide. The leaf stalks are red or at least show some red. There are no prominent stipules at the base of the leaf stalk. The blades are palmately lobed with usually 3, sometimes 5, lobes. The lobes taper to sharply-pointed tips. The space between the lobes (sinus) sharply V-shaped. The two bottom lobes, if present, are much smaller than the two lateral lobes. The lateral lobes are cut ¼ to ½ of the way to the base. The central lobe is more or less parallel-sided below the middle, widest at or just above the base, then tapered to the tip. The sinus at the base of the leaves is open and the two bottom lobes do not overlap. The upper surface is light green and hairless. The lower surface of young leaves is paler green and hairless or sparsely hairy. The lower surface of mature leaves is often strongly whitened, glaucous, and hairless or sparsely hairy along the main veins. The margins are irregularly toothed, including inside the sinuses, sometimes appearing double-toothed. The teeth are small. The sides and tip of the leaf do not droop. In the fall the leaves turn scarlet red, orange, or yellow. Fallen leaves break down quickly.

The inflorescence is a short, dense cluster of flowers from lateral buds on the branches. Male and female flowers are borne on the same tree and but on different branches. They appear identical, having both stamens and pistils, but usually only one of the organs is functional. They are produced in late March to May, long before the leaves appear. The flowers are pollinated by wind and bees.

The fruit is a pair of dry seed cases with papery wings attached (double samara). They occur in clusters that droop downward from long stalks. The stalks are longer than the wings. Each double samara is more or less in the shape of an inverted U, connected at the top with the wings spreading apart at about a 60° angle. The sometimes appear parallel or almost parallel. Individual samaras (or keys) are ¾ to 1½ long and hairless. They are slightly connected to each other when young and separated at maturity. The seed cases are plump. The wings are typically ½ to 1 long. The keys are green initially, turning red as they age, then tan when they are mature. They mature from April to June before leaf development is complete. They fall during a 1 to 2 week period from April to July. Paired keys are shed individually. Usually only one seed case contains a single, viable seed, although sometimes both contain seeds, sometimes both are empty.

 
     
 

Height

 
 

40 to 70

 
     
 

Record

 
 

The champion red maple in Minnesota is on state property near Kerrick, in Pine County. In 2009 it was measured at 80 tall and 95 in circumference (30 in diameter).

 
     
 

Flower Color

 
 

Red

 
     
 

Similar Species

 
  Mountain maple (Acer spicatum) is usually a tall shrub, sometimes a small tree. The terminal lobe of the leaf is less than half the length of the entire blade, and is tapered along the sides all the way to the crotch. The inflorescence is an erect, 1½ to 3 long spike.  
     
 
Habitat
 
 

Wet to dry. Swamps, upland woods.

 
     
 
Biology
 
 

Flowering

 
 

March to May

 
     
 

Pests and Diseases

 
 

Ocellate gall midge (Acericecis ocellaris) causes a flat, purple-ringed, yellow “eyespot” gall on the upper leaf surface.

Septoria Leaf Spot (Septoria aceris) produces dark brown or tan spots with light brown centers on the upper leaf surface.

Tar Spot (Rhytisma americanum) forms few large black spots on maple leaves.

 
     
 
Use
 
 

Toxicity

 
 

The leaves of red maple are extremely toxic to horses.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 7, 8, 28.

 
  6/15/2013      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

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 (dicots)  
  Subclass Rosidae  
  Superorder Rosanae  
 

Order

Sapindales (soapberries, cashews, mahoganies, and allies)  
 

Family

Sapindaceae (soapberry)  
  Subfamily Hippocastanoideae  
  Tribe Acereae  
 

Genus

Acer (maple)  
  Section Rubra  
  Species Acer rubrum (red maple)  
       
 

Synonyms

 
 

Acer rubrum var. tomentosum

Acer stenocarpum

Rufacer rubrum

 
       
 

Common Names

 
 

Carolina red maple

Drummond red maple

red maple

scarlet maple

soft maple

swamp maple

water maple

 
       

 

 

 

 

 

 

 

 

Glossary

Bundle scar

Tiny raised area within a leaf scar, formed from the broken end of a vascular bundle.

 

Glaucous

Pale green or bluish gray due to a whitish, powdery or waxy film, as on a plum or a grape.

 

Lenticel

A corky, round or stripe-like, usually raised, pore-like opening in bark that allows for gas exchange.

 

Palmate

Similar to a hand. Having more than three lobes or leaflets that radiate from a single point at the base of the leaf.

 

Samara

A dry fruit consisting of a seed attached to a papery wing; one seeded in Elms and Ashes, two-seeded in Maples.

 

Sinus

A space, indentation, or cleft, usually on a leaf, between two lobes or teeth.

 

Stipule

A small, leaf-like, scale-like, glandular, or rarely spiny appendage found at the base of a leaf stalk, usually occurring in pairs and usually dropping soon.

       
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Bark

  red maple    
       

Buds

  red maple    
       

Leaves

  red maple   red maple
       
  red maple    
       
       

 

Camera

     
Slideshows
   
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About

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Identify that Plant
 
   
 
About

Published on May 22, 2014

A detailed look at characteristics of Red maple (Acer rubruum). These images and narrative can help to accurately identify the plant during different seasons of the year.

 
     

 

slideshow

       
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Other Videos
 
  Trees with Don Leopold - red maple
ESFTV
 
   
 
About

Uploaded on Sep 23, 2011

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