Betula kenaica

W. H. Evans

Bot. Gaz. 27: 481. 1899.

Common names: Kenai birch
Endemic
Synonyms: Betula kamtschatica var. kenaica (W. H. Evans) C. A. Jansson Betula neoalaskana var. kenaica (W. H. Evans) B. Boivin Betula papyrifera var. kenaica (W. H. Evans) A. Henry
Treatment appears in FNA Volume 3.

Trees, to 12 m; crowns narrow. Bark dark reddish-brown, sometimes becoming pinkish or grayish white, smooth, in maturity exfoliating in thin sheets; lenticels dark, horizontally expanded. Twigs without taste and odor of wintergreen, slightly to moderately pubescent, often with scattered resinous glands. Leaf-blade ovate to nearly deltate with 2–6 pairs of lateral-veins, 4–5 (–7.5) × 2.5–4.5 cm, base rounded to cuneate, margins coarsely doubly serrate to dentate, teeth relatively sharp, apex acute to short-acuminate; surfaces abaxially sparsely to moderately pubescent, especially along major veins and in vein-axils, often with scattered resinous glands. Infructescences erect to nearly pendulous, cylindric, 2–5 × 0.5–1 cm, shattering with fruits in fall; scales ciliate, lobes diverging at middle, nearly equal in length, strongly divergent. Samaras with wings as broad as to somewhat narrower than body, broadest near middle, not extended beyond body apically. 2n = 70.


Phenology: Flowering late spring.
Habitat: Rocky slopes in the subalpine zone
Elevation: 0–300 m

Discussion

The relationship of Betula kenaica to other white-barked birches is not well understood, although it and the following species are evidently closely allied to B. papyrifera, from which they have likely been derived. Betula kenaica differs from B. papyrifera primarily in its smaller stature and in its smaller, blunter-tipped, more coarsely and regularly serrate leaves.

Betula ×hornei Butler (= Betula kenaica W. H. Evans × B. nana Linnaeus), variously intermediate between its parents, is common throughout the range of B. kenaica (which is mostly overlapped by that of B. nana).

Selected References

None.

Lower Taxa

None.

"equal" is not a number."broadest" is not a number. "somewhat narrower" is not a number.

... more about "Betula kenaica"
John J. Furlow +
W. H. Evans +
tanniferous +  and furrowed +
grayish white +, pinkish +  and dark reddish-brown +
exfoliating +
rounded +  and cuneate +
2 (?) +  and 3 (?) +
slender +
staminate +  and pistillate +
solitary +  and in small racemose clusters +
ovoid +  and cylindric +
expanding +
Kenai birch +
multibracteate +
Yukon +  and Alaska. +
0–300 m +
pistillate +  and staminate +
expanding +
small +  and large +
Rocky slopes in the subalpine zone +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
erect;nearly pendulous +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
membranaceous +
5 cm50 mm <br />0.05 m <br /> (7.5 cm75 mm <br />0.075 m <br />) +
4 cm40 mm <br />0.04 m <br /> (5 cm50 mm <br />0.05 m <br />) +
2.5 cm25 mm <br />0.025 m <br /> (4.5 cm45 mm <br />0.045 m <br />) +
not obvious +  and defined +
membranaceous +
Flowering late spring. +
2(-3)-carpellate +
1-seeded +  and 2-winged +
not extended +
crowded +  and imbricate +
deciduous +
(1-)3-lobed +
expanding +
not woody +  and leathery +
exfoliating +
2 (?) +  and 3 (?) +
nearly +  and distinct +
Betula kamtschatica var. kenaica +, Betula neoalaskana var. kenaica +  and Betula papyrifera var. kenaica +
Betula kenaica +
species +
excurrent +  and branching +
differentiated +
somewhat narrower +
tanniferous +
light +, nearly white +  and reddish-brown +
soft +  and hard +