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alaskan bunchberry, western bunchberry, western cordilleran bunchberry

cornouiller oblique, pale dogwood, silky dogwood

Habit Shrubs, to 5 m, flowering at 1.5 m; rhizomes absent.
Stems

erect, green, 6–22 cm, appressed-hairy;

nodes 4–6, internodes progressively longer distally;

branches only at distalmost node, much shorter than distal internodes so stems appear unbranched.

clustered, branches occasionally arching to ground and rooting at nodes;

bark green-tan or maroon-tan, not corky, appearing braided, splitting longitudinally;

branchlets green abaxially, maroon to green adaxially, turning red-maroon in fall, densely erect-hairy when young;

lenticels not protruding on 2d year branches, area surrounding them not suffused with purple on older branches;

pith tan or brown.

Leaves

at proximal 2–4 nodes nonchlorophyllous, opposite, ± scalelike, caducous (rarely chlorophyllous at 3d node from apex but much smaller than more distal leaves), at 2d node from apex nonchlorophyllous proximally, chlorophyllous distally, opposite, well developed, persistent, at distalmost node chlorophyllous, appearing to be in whorl of 6, well developed, persistent;

distalmost leaves much bigger than those at 2 more proximal nodes;

petiole 0–3.4 mm;

blade ovate to elliptic, 3.5–8 × 0.9–4 cm, apex acute or short acuminate, abaxial surface pale green, hairs sparsely appressed-hairy, adaxial surface green, appressed-hairy;

secondary veins 3 per side, all arising from proximal 1/2.

petiole 6–20 mm;

blade lanceolate to narrowly elliptic, 4–12 × 1–5 cm, base cuneate, apex acuminate, abaxial surface pale whitish yellow, hairs white, all appressed and rigid, tufts of hairs absent in axils of secondary veins, midvein and secondary veins densely tomentose, adaxial surface dark green, hairs appressed;

secondary veins (4–)5–6 per side, evenly spaced, tertiary veins not prominent.

Inflorescences

20–40-flowered;

peduncle 13–30 mm;

primary branches 0–2 mm;

bracts greenish white or white, often red-tipped, unequal, 2 ovate, 21–30 × 12–13 mm, 2 suborbiculate, 17–1.9 × 13–16 mm, apex acuminate.

flat-topped or convex, 2–7 cm diam., peduncle 20–70 mm;

branches and pedicels green or greenish yellow, turning maroon in fruit.

Pedicels

0.4–1.6 mm, sparsely appressed-hairy or glabrous.

Flowers

hypanthium cream to mottled purple, 1.2–2 mm, densely appressed-hairy;

sepals mottled purple and cream, 0.1–0.4 mm, apex rounded or acute, thick, sparsely hairy on margin, densely glandular;

petals cream proximally, purple distally, 1.5–1.8 mm, apical awn 0.4–0.6 mm;

nectary dark purple or black.

hypanthium densely appressed-hairy, especially at base;

sepals 1–2.3 mm;

petals cream, 3.8–5 mm.

Drupes

10–20 per inflorescence, red, globose, 6–8 mm;

stone globose or subglobose, 2.7–3.4 × 2.1–3.4 mm, longitudinally grooved, apex slightly pointed.

blue, portion in direct sunlight bleached white, globose, 5–9 mm diam.;

stone globose, 4–6 mm diam., irregularly longitudinally ridged, apex pointed.

2n

= 44.

= 22

Cornus unalaschkensis

Cornus obliqua

Phenology Flowering May–Aug; fruiting Aug–Oct. Flowering May–Aug; fruiting Aug–Oct.
Habitat Maritime copse or heath, maritime coniferous forests and bog woodlands, moist broadleaf or coniferous forests. Alluvial woods, river and stream banks, wet meadows, marshes, ditches.
Elevation 0–3000 m. (0–9800 ft.) 0–1500 m. (0–4900 ft.)
Distribution
from FNA
AK; CA; ID; OR; WA; AB; BC; YT
[WildflowerSearch map]
[BONAP county map]
from FNA
AR; CT; DC; IA; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; ND; NE; NH; NJ; NY; OH; OK; PA; RI; SD; TN; VA; VT; WI; WV; NB; ON; QC
[BONAP county map]
Discussion

H. W. Rickett (1934) argued that the description of Cornus obliqua by Rafinesque is inadequate to associate that name with a species; that assessment is not accepted here. The description by Rafinesque of the plants having reddish brown, slightly rugose bark, narrowly elliptic to lanceolate discs, and whitish yellow abaxial leaf surfaces, along with the cited locality of the Kentucky River, clearly delineates this species. Rafinesque was the first to divide the blue-fruited dogwood of L. Plukenet (1691–1705, part 4) into two species.

Cornus obliqua and C. amomum can be distinguished not only by the differences included in the key above, but also by their abaxial leaf cuticle, which is coronulate in C. obliqua but not in C. amomum, but seeing this character requires high magnification. However, in much of the area where they are sympatric (Connecticut, District of Columbia, Maine, Maryland, Massachusetts, New Hampshire, New York, Tennessee, and Vermont), many individuals show intermediate leaf blade abaxial surface and hair morphology. They are detected by having both the whitish leaf blade abaxial surface and appressed hairs of C. obliqua with occasional scattered erect, often tan to brown hairs, similar to those typical for C. amomum. J. S. Wilson (1964) concluded that differences in leaf surface and hair morphology are environmentally based (sun versus shade), whereas work by Z. E. Murrell (1992) documented a geographical basis for the differences. The geographical zone of intermediacy needs greater scrutiny to determine its full extent and whether the intermediacy of many plants represent hybridization or incomplete speciation.

A putative hybrid between Cornus obliqua and C. racemosa, reported from Massachusetts, Ohio, and Pennsylvania, has been called C. ×arnoldiana Rehder [= Swida arnoldiana (Rehder) Soják].

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 12, p. 448. FNA vol. 12, p. 452.
Parent taxa Cornaceae > Cornus > subg. Arctocrania Cornaceae > Cornus > subg. Thelycrania
Sibling taxa
C. alternifolia, C. amomum, C. asperifolia, C. canadensis, C. drummondii, C. florida, C. foemina, C. glabrata, C. kousa, C. mas, C. nuttallii, C. obliqua, C. occidentalis, C. racemosa, C. rugosa, C. sanguinea, C. sericea, C. sessilis, C. suecica
C. alternifolia, C. amomum, C. asperifolia, C. canadensis, C. drummondii, C. florida, C. foemina, C. glabrata, C. kousa, C. mas, C. nuttallii, C. occidentalis, C. racemosa, C. rugosa, C. sanguinea, C. sericea, C. sessilis, C. suecica, C. unalaschkensis
Synonyms Arctocrania unalaschkensis, Chamaepericlymenum unalaschkense, Cornella unalaschkensis, Swida unalaschkensis C. amomum subsp. obliqua, C. amomum var. schuetzeana, C. purpusii, Swida purpusii
Name authority Ledebour: Fl. Ross. 2: 378. (1844) Rafinesque: W. Rev. & Misc. Mag. 1: 229. (1819)
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