Alnus x pubescens
Common Name(s):
Previously known as:
- Alnus balatonialis
- Alnus glutinosa var. pubescens
- Alnus × hybrida
- Alnus incana var. glabrescens
- Alnus x ambigua
- Alnus x beckii
- Alnus x montana
- Alnus x spuria
- Alnus x tauschiana
- Phonetic Spelling
- AL-nus pew-BES-ens
- Description
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In 1834 Ignaz Tausch described and published the name Alnus x pubescens. It is a hybrid between the two species of deciduous trees, Alnus glutinosa (Black or European Alder) and Alnus incana (Grey Alder). The Hybrid Alder may be found in Austria, Czechoslovakia, Denmark, Finland, France, Germany, Great Britain. Ireland, Italy, Netherlands, North European Russia, Norway, Poland, and Sweden. It has been introduced in Belgium and Central European Russia. These hybrids are difficult to identify because of the overlapping characteristics of their parents. A distinctive feature is that the Hybrid Alder typically has a higher gland density on the undersurface of its leaves than its parents. The undersides of the Hybrid Alder's leaves are downy, particularly along the veins. Young growth is also downy.
The parent, Grey Alder, is generally smaller and more shrub-like than the Black Alder. Both parents have green leaves that have a downy or hairy underside. They also have both male and female flowers in the spring. The male flower is a catkin that is narrow and long. The female catkin develops into a cluster of woody cones. The seeds inside the cones are very small samaras. In the fall the seeds ripen and are dispersed by the wind. Both parents may be found in wetlands or along streams or rivers. Both prefer moist soils and can tolerate a wide range of soil types. The tree roots of both species add nitrogen to the soil by forming a relationship with nitrogen-fixing bacteria. The Grey Alder typically grows at higher elevations in central Europe than the Black Alder.
Where the Grey and Black Alder overlap they may occasionally form hybrids. This is usually uncommon since they do not flower at the same time. The Grey Alder typically flowers about a week earlier than the Black Alder.
The hybrid is a tough, adaptable plant, and has few pest problems. It tolerates short-term flooding.
The Hybrid Alder is reportedly very vulnerable and requires protection since this species occurs infrequently in nature.
- See this plant in the following landscape:
- Cultivars / Varieties:
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- Tags:
- Cultivars / Varieties:
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Attributes:
- Genus:
- Alnus
- Family:
- Betulaceae
- Life Cycle:
- Woody
- Country Or Region Of Origin:
- Europe and North European Russia
- Distribution:
- Austria, Belgium, Czechoslovakia, Denmark, Finland, France, Germany, Great Britain. Ireland, Italy, Netherlands, North and Central European Russia, Norway, Poland, and Sweden
- Dimensions:
- Height: 20 ft. 0 in. - 30 ft. 0 in.
- Width: 10 ft. 0 in. - 20 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Tree
- Woody Plant Leaf Characteristics:
- Deciduous
- Habit/Form:
- Rounded
- Texture:
- Medium
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- Loam (Silt)
- Soil pH:
- Acid (<6.0)
- Soil Drainage:
- Good Drainage
- Moist
- Occasionally Wet
- USDA Plant Hardiness Zone:
- 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b
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Fruit:
- Fruit Color:
- Brown/Copper
- Fruit Value To Gardener:
- Long-lasting
- Display/Harvest Time:
- Fall
- Fruit Type:
- Samara
- Fruit Length:
- < 1 inch
- Fruit Width:
- < 1 inch
- Fruit Description:
- The female catkins develop into wood cones. Inside the cones are winged seeds that are released in the fall when they have matures.
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Flowers:
- Flower Color:
- Orange
- Red/Burgundy
- Flower Inflorescence:
- Catkin
- Flower Value To Gardener:
- Showy
- Flower Bloom Time:
- Spring
- Flower Description:
- The Hybrid Alder produces male and female florets on the same tree. The male florets have clusters of catkins which are reddish-orange, long, and drooping. The female florets are clusters of cone-like catkins.
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Green
- Leaf Feel:
- Glossy
- Leaf Type:
- Simple
- Leaf Arrangement:
- Alternate
- Leaf Shape:
- Orbicular
- Leaf Margin:
- Dentate
- Hairs Present:
- Yes
- Leaf Length:
- 1-3 inches
- Leaf Width:
- 1-3 inches
- Leaf Description:
- The leaves are green and orbicular in shape. The margins are dentated. The undersurface of the leaves is hairy, particularly along the leaf veins. There is also a higher gland density on the undersurface.
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Stem:
- Stem Is Aromatic:
- No
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Landscape:
- Landscape Location:
- Coastal
- Pond
- Riparian
- Landscape Theme:
- Rain Garden
- Winter Garden
- Resistance To Challenges:
- Insect Pests
- Poor Soil
- Wet Soil
