Betula papyrifera subsp. humilis (Regel) Hult.
 
FamilyBetulaceae — APG family: Betulaceae
SynonymsBetula alba var. humilis Regel, Betula papyrifera var. humilis (Regel) Fern., Betula resinifera Britt., Betula papyrifera var. neoalaskana (Sarg.) Raup, Betula alaskana Sarg., Betula neoalaskana Sarg.
Common namepaper birch
DescriptionTree, usually 10-15, rarely up to 20, meters tall; with trunk up to 60 cm in di- ameter and white bark; young twigs strongly resiniferous; leaves yellowish-green, ovate, with elongated apex and cuneate or truncate base, serrate, glabrous above and in margin, resin-dotted below, with tufts of hairs in angles of nerves below; ~ catkins short, thick, greenish-brown; bracts with median lobe usually longer than the blunt, diamond-shaped, lateral lobes; nutlets with wings broader than body.
EcologyCommon in the lowlands; to 800 meters in McKinley Park; to 1,200 meters in the Yukon.
Taxonomy
notes
No type locality given for B. papyrifera; subsp. humilis described from Saskatchewan. Forms hybrid swarms with B. kenaica as well as hybrids with B. nana subsp. exilis and B. glandulosa.
Hultén's Flora About

This is a digital representation of Eric Hultén’s ‘Flora of Alaska and Neighboring Territories: A Manual of the Vascular Plants’, which was published by Stanford University Press in 1968. The book was digitized by C. Webb (at UAMN) as part of the Flora of Alaska project, with funding by the US NSF (Grant 1759964 to Ickert-Bond & Webb), and with permission of Stanford University Press. Data and images © 1968 Board of Trustees of the Leland Stanford Jr. Univ. Usage licence: Creative Commons BY-NC-SA 4.0. NB: You may find OCR errors; please refer to the hard-copy if in doubt.