Alnus serrulata

Species Native to Missouri
Common Name: hazel alder 
Type: Tree
Family: Betulaceae
Native Range: Eastern United States
Zone: 4 to 9
Height: 10.00 to 20.00 feet
Spread: 8.00 to 15.00 feet
Bloom Time: March to April
Bloom Description: Brownish-yellow (male) and red (female)
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Low
Suggested Use: Naturalize, Rain Garden
Flower: Showy
Tolerate: Clay Soil, Wet Soil

Culture

Best grown in medium to wet soils in full sun to part shade. Tolerates mucky soils. Avoid full shade. Winter hardy to UDSA Zones 4-9.

Noteworthy Characteristics

Alnus serrulata, commonly called tag alder, smooth alder or hazel alder, is a multi-stemmed, suckering, thicket-forming, large deciduous shrub or small tree that typically grows to 10-20’ tall. It is most often seen in a multi-trunked form with a densely branched crown. It is native to boggy ground along streams/lakes/rivers, wetland margins, springs, spring-fed meadows, ditches and swampy fields from Nova Scotia to Illinois and Missouri south to eastern Texas and northern Florida.

Trunks feature smooth gray bark with inconspicuous lenticels (pores). Flowers are monoecious (separate male and female flowers on the same tree), appearing in separate catkins in March-early April before the leaves emerge. Male catkins (brownish-yellow flowers) are slender, cylindrical and droop in clusters of 2-5 from near the branch tips to 2-4" long. Female catkins (bright red flowers) are upright cylinders (to 1/4" long) located at the twig tips in clusters of 2-5. Female flowers are pollinated by wind. Female catkins develop into 1-inch long fruiting cones (strobiles) to 3/4” long containing winged nutlets (seeds). Fruiting cones mature to dark brown in fall, with persistence into winter. Cones have woody scales and resemble small pine cones. Birds feed on the seed. Broad elliptic to obovate dull green leaves (2-4" long) with serrulate margins are wedge-shaped at the base and pointed at the tip. Insignificant fall color. Root nodules fix nitrogen.

Alnus serrulata is very similar in appearance to Alnus incana subsp. rugosa.

Genus name is the Latin name for alder.

Specific epithet is in reference to serrulate leaf margins.

Problems

No serious insect or disease problems. Canker can be severe. Powdery mildew and leaf curl may appear. Watch for aphids, leaf miners, tent caterpillars, lace bugs and flea beetles. Chlorosis will occur in high pH soils.

Garden Uses

Best for moist areas of the landscape. Tolerates poor soils. Streambanks. Pond margins.