Jepson eFlora: Taxon page
Vascular Plants of California
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Tsuga mertensiana

Higher Taxonomy
Family: PinaceaeView DescriptionDichotomous Key
Common Name: PINE FAMILY
Habit: Shrub, tree, evergreen; monoecious. Stem: young crown conic; twig not grooved, resinous, generally persistent. Leaf: simple, generally alternate, sometimes in bundles or appearing +- 2-ranked, linear or awl-like; base decurrent, woody or not, persistent several years. Pollen Cone: generally < 6 cm, not woody, deciduous. Seed Cone: generally woody; bracts, scales generally persistent; scale not peltate, fused to or free from subtending bract. Seed: 2, on scale base adaxially.
Genera In Family: 10 genera, 193 species: generally northern hemisphere; many of great commercial value, supplying > 1/2 of world's timber.
eFlora Treatment Author: J. Robert Haller, Nancy J. Vivrette, & James R. Griffin, except as noted
Scientific Editor: Thomas J. Rosatti, Bruce G. Baldwin.
Genus: TsugaView DescriptionDichotomous Key

Common Name: HEMLOCK
Stem: crown conic, top slender, generally nodding; branches +- drooping; bark red-brown; twig with persistent, peg-like leaf bases, hairy or puberulent; bud ovoid. Leaf: 5--25 mm, tapered to a short petiole above persistent base, spreading, +- 2-ranked or not, +- flat, grooved adaxially or not, ridged abaxially. Seed Cone: pendent, 1.2--7.5 cm, ovoid to oblong, opening 1st year; stalk +- 0; bract included, free from scale. Seed: plus wing < 2 cm. Chromosomes: 2n=24.
Etymology: (Japanese: hemlock)
Tsuga mertensiana (Bong.) Carrière
Stem: trunk < 35 m, 2.2 m wide, prostrate at timberline; mature bark red- or purple-brown, with narrow grooves between narrow ridges; twig puberulent. Leaf: 10--25 mm, persistent < 7 years, tip rounded.
Ecology: Subalpine, some scattered in cold areas of red-fir, mixed-conifer forest; Elevation: 1200--3500 m. Bioregional Distribution: KR, NCoRH, CaRH, SNH, MP, n SNE; Distribution Outside California: to Alaska, Montana.
Jepson eFlora Author: J. Robert Haller, Nancy J. Vivrette, & James R. Griffin
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

Previous taxon: Tsuga heterophylla
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Botanical illustration including Tsuga mertensiana

botanical illustration including Tsuga mertensiana

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Citation for this treatment: J. Robert Haller, Nancy J. Vivrette, & James R. Griffin 2012, Tsuga mertensiana, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on April 24, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora,, accessed on April 24, 2024.

Tsuga mertensiana
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©2012 Julie Kierstead Nelson
Tsuga mertensiana
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©2008 Neal Kramer
Tsuga mertensiana
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©2015 Neal Kramer
Tsuga mertensiana
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©2015 Neal Kramer
Tsuga mertensiana
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©2015 California Academy of Sciences

More photos of Tsuga mertensiana
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Geographic subdivisions for Tsuga mertensiana:
1. You can change the display of the base map layer control box in the upper right-hand corner.
2. County and Jepson Region polygons can be turned off and on using the check boxes.
map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).


Data provided by the participants of the  Consortium of California Herbaria.
View all CCH records
All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.

CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).