Betula occidentalis

Taxobox
name = "Betula occidentalis"
status = secure

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image_width = 240px
image_caption = Foliage
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Fagales
familia = Betulaceae
genus = "Betula"
subgenus = "Betula"
species = "B. occidentalis"
binomial = "Betula occidentalis"
binomial_authority = Hook.
synonyms=
*"B. fontinalis" Sarg.

"Betula occidentalis (Water Birch"') is a species of birch native to western North America, in Canada from Yukon east to western Ontario and southwards, and in the United States from eastern Washington east to western North Dakota, and south to eastern California, northern Arizona and northern New Mexico, and also possibly eastern Alaska (but see below). It typically occurs along streams in mountainous regions.Flora of North America: [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500259 "Betula occidentalis"] ]

It is a deciduous shrub or small tree growing to 10 m high, usually with multiple trunks. The bark is dark red-brown to blackish, and smooth but not exfoliating. The twigs are glabrous or thinly hairy, and odorless when scraped. The leaves are alternate, ovate to rhombic, 1-7 cm long and 1-4.5 cm broad, with a serrated margin and two to six pairs of veins, and a short petiole up to 1.5 cm long. The flowers are wind-pollinated catkins 2-4 cm long, the male catkins pendulous, the female catkins erect. The fruit is 2-3 cm long and 8–15 mm broad, composed of numerous tiny winged seeds packed between the catkin bracts.Plants of British Columbia: [http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Betula+occidentalis "Betula occidentalis"] ] Jepson Flora: [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?Betula+occidentalis "Betula occidentalis"] ]

The identity of similar birches in eastern Alaska is disputed; some include them in "B. occidentalis", while others regard them as hybrids between "Betula neoalaskana" and "Betula glandulosa".

References