Maple Trees

Acer spp.



There are five species of the Maple family (Aceraceae) that are native to Texas which include the Southern Sugar Maple (Acer floridanum), Big-toothed Maple (Acer grandidentatum), Chalk Maple (Acer leucoderme), Boxelder or Ash-leaved Maple (Acer negundo), and Red Maple (Acer rubrum).    The Southern Sugar Maple is a small, spreading tree reaching 20 to 25 ft or 6 to 7.5 m tall. Its fall color is usually yellow and is not as vibrant. Its lobed leaves are green above and paler below. Small flowers hang from a stalk in clusters and are yellow to green in color. The samara fruit is ¾ inches long and matures in mid-summer.    Bigtooth Maple is a shrubby or tree-like maple that matures around 10 to 15 ft or 3 to 4.5 m tall. Its bark is dark brown and scaly. The branches are stout and erect. The lobed leaves are dark green on top and pale underneath which turn bright red or gold in the fall. It has a short trunk with a spreading, round, and dense crown. Flowers are inconspicuous, hang in clusters, appear with leaves, and are yellow to green in color.    The Chalk Maple grows to 25 ft or 7.6 m tall and typically has two to three trunks. Its mature bark is chalkily surfaced with a distinct white color. Its leaves may be smaller than other maple species, drooping, and gray-green underneath. Bloom time occurs from April to May with yellow flowers. Its fruit is a reddish-brown samara.    The Box Elder grows from 35 to 50 ft or 10.5 to 15 m tall. It commonly has a short trunk with wide-spreading branches. It differs from the other maple species since it has compound leaves with 3 to 9 leaflets. Young trees and new growth are bright olive-green. Its foliage color is insignificant in the fall. Blooming occurs from March to April with flowers being yellow, green, or brown in color, inconspicuous, in clusters, and appearing as leaves start to unfold. Its fruit is a one-seeded samara that droops in clusters.    Red Maple trees typically grow 40 to 60 ft or 12 to 18 m; however, they can reach heights over 100 feet or 30 meters. The Red Maple, often planted as an ornamental, has pink to red flowers borne in the spring, before the leaves. Its three to five-lobed leaves are opposite each other on the stem, bright green above and whitish beneath. Leaves can be either smooth or hairy. The fruit is a samara that grows in pairs and is reddish to brown in color. Red Maples provide fall color as the leaves turn shades of yellow through orange or red. 


The Southern Sugar Maple can be found from Virginia to Florida, West to Kansas, and South to eastern Texas. Native habitats include streams and riverbanks. It is resistant to wind and ice.    Bigtooth Maples are found in the western United States. In Texas, they are found in the Trans-Pecos and Edwards Plateau regions. Native habitats include moist soils of canyons and woodlands.    The Chalk Maple can be found in rocky woods, river bluffs, or ravines. It displays tolerance to dry soil, but it needs moisture in brighter growing sites.    Box Elders are distributed across the United States, Canada, and Mexico. It is intolerant of drought. Native habitats include moist woods, stream banks, and floodplains.    Red Maple trees may be found throughout the entire eastern half of the United States and Canada, including all regions of Texas. Red Maple can grow in most soils but grows better in slightly acidic and moist conditions.  

Toxic Agent

The toxic agent of maple has not been identified. The toxin in Red Maples oxidizes the hemoglobin with the formation of Heinz bodies, methemoglobinemia, and following hemolytic anemia. Only the Red Maple and closely related hybrids are known to be toxic, but all species of maple should be considered potentially toxic to horses. Feeding studies have confirmed the toxicity of Red Maple. Most of the intoxications reported have dealt with red maple, but field cases are also reported involving the consumption of Silver Maple with similar clinical signs. Poisoning occurs when horses consume wilted or dry leaves equivalent to 1.5 to 3.0 grams of dry leaves per kilogram of body weight, or about 2 pounds of dry leaves for a 1,000-pound horse. Fresh green leaves are not toxic but can remain toxic for up to 30 days once dried. Some animals have been poisoned after consuming bark; poisoning usually follows windstorms after which downed trees and limbs become available to the horses. Most cases of maple intoxication occur during the late spring, summer, or early fall. 

Signs of Livestock Ingestion

Horses consuming maple may have hemolytic anemia and usually show clinical signs within 12 to 48 hours. The most prominent signs are: Yellow or brown mucous membranes; Depression; Anorexia; Weakness; Red or brown urine. Fatally affected horses usually die within 7 days. Sick animals may have Heinz body anemia for 2 to 3 weeks before recovery.

Management Strategies

Never place limbs trimmed from Maple trees in an area accessible to horses. Check horse pastures or paddocks containing maples for downed branches after a windstorm. Remove any damaged Maple before it can be consumed.