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White Alder
Alnus rhombifolia
  
About White Alder (Alnus rhombifolia) 43 Nurseries Carry This Plant White Alder (Alnus rhombifolia) is a member of the Birch family (Betulaceae) native to western North America, from Washington east to western Montana and south to San Diego County, occurring at altitudes of 300-7900 feet. Though not reported from northern Baja California, it has been predicted to occur there on the basis of its climatic adaptation.

White Alder is a medium-sized deciduous tree. Its pale gray bark is smooth on young trees, becoming scaly on old trees.

The flowers are produced in catkins. The male catkins are pendulous, slender, 1 to 4 inches long, yellowish, and produced in clusters of two to seven. Pollination happens in early spring, before the leaves emerge. The tree produces very large amounts of pollen at this time.

The female catkins are ovoid and mature in autumn, superficially resembling a small conifer cone. The small winged seeds disperse through the winter, leaving the old woody, blackish 'cones' on the tree for up to a year after.

Plant White Alders in moist soils or on the edges of permanently wet areas such as streambanks or edges of regularly irrigated area. These trees grow quickly to 20 feet, and then more slowly. The roots can be invasive, so use caution in deciding where to plant. Due to its ultimate size, White Alder may not be appropriate for small residential gardens.
Plant Description
Plant Type
Plant Type
Tree

Size
Size
49.2 - 82 ft tall
35 ft wide

Form
Form
Upright, Rounded, Upright Columnar

Growth Rate
Growth Rate
Fast

Dormancy
Dormancy
Winter Deciduous

Fragrance
Fragrance
Fragrant - Pleasant

Flower Color
Flower Color
Green, Cream

Flowering Season
Flowering Season
Fall, Summer

Wildlife Supported
 


Landscaping Information
Sun
Sun
Full Sun, Part Shade

Moisture
Moisture
Moderate - High

Summer Irrigation
Summer Irrigation
Keep moist

Nurseries
Nurseries

Soil Drainage
Soil Drainage
Fast, Medium, Slow

Soil Description
Soil Description
Tolerant of sand and clay. Soil PH: 4.0 - 8.0

Common uses
Common uses
Bird Gardens, Butterfly Gardens

Companion Plants
Companion Plants
Wetland-riparian trees and plants including Maples (Acer spp.), Dogwood (Cornus spp.), Ash (Fraxinus spp.), Walnut (Juglans spp.), Western Sycamore (Platanus racemosa), Cottonwood (Populus spp.), Willow (Salix spp.), Spicebush (Calycanthus occidentalis), Wild Honeysuckle (Lonicera spp.), Wild Azalea (Rhododendron spp.), Wild Currant (Ribes spp.), Wild Rose (Rosa spp.), and Wild Grape (Vitis spp.).

Sunset Zones
Sunset Zones?
1*, 2*, 3*, 4, 5, 6, 7*, 8, 9*, 10, 14*, 15*, 16*, 17*, 18*, 19, 22*, 23*, 24*

Natural Setting
Site Type
Site Type
Usually found in wetland such as permanent stream edges, often adjacent to other vegetation such as chaparral, redwood forest, pine forest, and foothill woodland

Climate
Climate
Annual Precipitation: 4.8" - 153.6", Summer Precipitation: 0.14" - 5.72", Coldest Month: 23.6" - 59.1", Hottest Month: 44.8" - 87.7", Humidity: 0.02" - 38.56", Elevation: -7" - 10807"


Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora


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