Alnus serrulata (Smooth alder)

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Alnus serrulata (Aiton) Willd.

Smooth alder, hazel alder

Plants: 8–13′ (2.5–4 m) tall, somewhat disheveled-looking trees, with many trunks and branches that form a nearly impenetrable thicket. Bark is smooth, lacking lenticels.

Leaves: 2–5 ⨉ 1–2½″ (5–12 ⨉ 3–7.1 cm), obovate, with rounded edges or small serrations, dark green above, paler and with fine hairs below.

Flowers: Bright yellow in spring, becoming brown-green, male catkins hang in groups of 2-5, and are 2–4″ (5–10 cm) long. Female flowers, also catkins, are upright, cylindrical, up to ¼″ (6.3 mm) long, and bright red or reddish-green. Flowers appear from March to April.

Fruits: Small cone-like fruits called strobiles, which remain on the tree through the winter. They are up to ¾″ (1.9 cm) long, containing winged nutlets.

Habitats: Moist soil near streams, pond margins, and riversides.

Online References:

Carolina Nature

The Virginia Tech Department of Forest Resources and Environmental Conservation

North Carolina Extension Gardener Plant Toolbox

The Lady Bird Johnson Wildflower Center

Plants for a Future

Flora of North America

References:

Sibley, David Allen, The Sibley Guide to Trees, Alfred A. Knopf, 2009, pp. 159-165

Little, Elbert L., National Audubon Society Field Guide to North American Trees, Eastern Region, Alfred A. Knopf, 1980, p. 363-4

Alnus incana (L.) Moench var. serrulata (Aiton) B. Boivin
Alnus noveboracensis Britton
Alnus serrulata (Aiton) Willd. var. subelliptica Fernald

9/6/2025 · Camp at Sebago Lake, Standish, Maine · ≈ 1½ × 1′ (54 × 36 cm)

4/27/2023 · Mitchell Field, Harpswell, Maine

9/25/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 6 × 4″ (15 × 10 cm) ID is uncertain

8/6/2017 · Andres Art Institute, Big Bear Mountain, Brookline, New Hampshire · ≈ 6 × 4″ (16 × 11 cm)

4/18/2021 · Tarbox Preserve, Topsham, Maine · ≈ 4 × 6″ (11 × 16 cm)

8/6/2017 · Andres Art Institute, Big Bear Mountain, Brookline, New Hampshire · ≈ 6 × 4″ (15 × 10 cm)

8/6/2017 · Andres Art Institute, Big Bear Mountain, Brookline, New Hampshire · ≈ 6 × 4″ (14 × 10 cm)

4/27/2023 · Mitchell Field, Harpswell, Maine

9/25/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 4 × 3½″ (10 × 8.6 cm) ID is uncertain

12/23/2009 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 15 × 10″ (37 × 25 cm)

8/6/2017 · Andres Art Institute, Big Bear Mountain, Brookline, New Hampshire · ≈ 6 × 4″ (14 × 10 cm)

9/25/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 4 × 5″ (10 × 13 cm) ID is uncertain

9/6/2025 · Camp at Sebago Lake, Standish, Maine · ≈ 14 × 10″ (36 × 24 cm)

Kingdom	Plantae	Plants, but not fungi, lichens, or algae (from Stearn's Botanical Latin)
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Rosidae	Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
Order	Fagales	Birch, she-oak, beech, walnut, bayberry, others
Family	Betulaceae	Birch family: birches, alders, hazels, hornbeams and hop-hornbeams
Genus	Alnus	The classical Latin name for this genus
Species	serrulata	Minutely serrate

About plant names...

Range: Zones 4-9:

About this map...

Alnus serrulata description by Thomas H. Kent, not updated.