Alnus rugosa (Du Roi) Spreng.
Alnus rugosa (Du Roi) Spreng. var. americana (Regel) Fernald
Alnus incana (L.) Moench ssp. rugosa (Du Roi) R.T. Clausen
Speckled alder, tag alder, hoary alder, gray alder
These fast-growing trees are often found beside wet areas. Alder roots, like many legumes, are capable of converting atmospheric nitrogen into usable nutrients, allowing them to grow in relatively infertile soil. These densely branched shrubs, with their penchant for growing in muddy soil and rapid spread by creating clonal colonies, form nearly impassable thickets.
Plants: Small to medium in size, often with multiple trunks and branches. Speckled alders grow to 12–36′ (3.7–10 m), rarely reaching 60′ (18 m), usually less than 20′ (6.1 m) tall. “Speckled” refers to the presence of many lenticels—white, or light gray or orange oval patches, wider than they are flat, on the trunk. The subspecies name, rugosa, means “wrinkled,” and refers to the network of sunken veins on the bottom surface of each leaf.
Leaves: Dark green, alternate, roughly oval, 2–4″ (5–10 cm) long, and doubly serrated.
Flowers: Male flowers are catkins 1½–3½″ (3.8–8.9 cm) long. Female flowers are cylindrical catkins attached directly to the branch, ⅛″ (4.8 mm) long.
Fruits: Egg-shaped cones about ⅝ ⨉ ¼″ (1.6 cm ⨉ 7.9 mm), green at first, becoming dark brown and often persisting through the winter.
Habitats: Moist areas, bordering streams, lakes and rivers; bogs and nutrient-rich swamps.
Online References:
Alnus incana (L.) Moench var. americana Regel
Alnus rugosa (Du Roi) Spreng.
Alnus rugosa (Du Roi) Spreng. var. americana (Regel) Fernald
Alnus rugosa (Du Roi) Spreng.
Alnus rugosa (Du Roi) Spreng. var. americana (Regel) Fernald
8/1/2009 · Stan & Connie’s, Falmouth, Maine · ≈ 8 × 7″ (19 × 17 cm) 
ID is uncertain 
10/17/2011 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 5 × 4½″ (13 × 11 cm) ID is uncertain 
10/16/2011 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 5 × 3½″ (12 × 9.4 cm) ID is uncertain 
10/16/2011 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 3½ × 3″ (9.3 × 8.4 cm) ID is uncertain 
8/4/2025 · Tarbox Preserve, Topsham, Maine · ≈ 7 × 4½″ (17 × 11 cm) 
8/4/2025 · Tarbox Preserve, Topsham, Maine · ≈ 6 × 4½″ (14 × 11 cm) 
8/1/2009 · Stan & Connie’s, Falmouth, Maine · ≈ 4½ × 3½″ (11 × 9.5 cm) ID is uncertain 
8/4/2025 · Tarbox Preserve, Topsham, Maine · ≈ 7 × 4½″ (18 × 12 cm) 
8/4/2025 · Tarbox Preserve, Topsham, Maine · ≈ 4½ × 7″ (12 × 18 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 | incana | Grayish or hoary |
| ssp. | rugosa | Wrinkled |
Alnus incana ssp. rugosa description by Thomas H. Kent, not updated.
© FloraFinder.org. All rights reserved.