OregonFlora: Vaccinium myrtillus vs. Vaccinium caespitosum

	Vaccinium myrtillus	Vaccinium caespitosum
	whortleberry	dwarf bilberry
Habit	Shrubs deciduous, up to 4 dm; branching habit open, rarely weakly “broom-like”; twigs strongly angled, green to greenish brown, sparsely puberulent along grooves, sometimes glabrous; rhizomatous.	Shrubs deciduous, up to 6 dm; twigs yellow-green to reddish, round in cross section to angled, glabrous to puberulent; rhizomatous.
Leaves	elliptic to ovate, 11–20(30) × 5–10 mm, light green abaxially, green adaxially; thin; flexible; margins sharply serrate from tips to near base, prominently veined; tips acute; surfaces abaxially glandular, adaxially glabrous.	obovate to oblanceolate, 10–30 × 3–12 mm; thin; flexible, green abaxially; margins serrate on distal 25–50%, prominently reticulate-veined; tips rounded, sometimes subacute; surfaces abaxially glabrous or glandular, adaxially glabrous.
Inflorescences	solitary flowers in axils.	solitary flowers in axils.
Flowers	sepals 5; calyces shallowly lobed, glabrous; petals 5; corollas ovoid-urceolate to globose, 3–7 × 4–7 mm, white to pink, glaucous; filaments glabrous.	sepals 5, light green; calyx lobes vestigial; petals 5; corollas cylindric-urceolate to globose, 4–6 × 3–5 mm, white to pink, glaucous; filaments > anthers, glabrous.
Fruits	4–9 mm in diameter, dark red to bluish black; without a bloom.	5–8 mm in diameter, blue to bluish black, with a bloom.
2n	=24, 48.	=24.

	Vaccinium myrtillus	Vaccinium caespitosum
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	Wet mid- to high elevation areas. Flowering Apr–Jul. 1100–2100 m. BW, Casc, Sisk. ID, NV, WA; northeast to Alberta and southeast to NM, Greenland; Asia, Europe. Native. Morphologically, Vaccinium myrtillus is similar to V. scoparium, and at higher elevations their ranges overlap. Vaccinium myrtillus differs from V. scoparium by its generally larger leaves and flowers, often sparsely puberulent twigs, and its broom-like habit.	Wet meadows to rocky mountain slopes. Flowering Apr–Aug. 50–2800 m. BR, BW, Casc, CR, ECas, Est, WV. CA, ID, WA; north to AK, east to Newfoundland, south to Guatemala. Native. Morphologically, V. caespitosum is very similar to V. deliciosum, making identification of these species difficult, particularly at higher elevations where their ranges overlap. The chromosome numbers of V. caespitosum (2n=24) and V. deliciosum (2n=48) may indicate that V. deliciosum is an autopolyploid derivative of V. caespitosum.
Source	Flora of Oregon, volume 2, page 640 Stephen Meyers	Flora of Oregon, volume 2, page 639 Stephen Meyers
Sibling taxa	V. caespitosum, V. corymbosum, V. deliciosum, V. macrocarpon, V. membranaceum, V. ovalifolium, V. ovatum, V. oxycoccos, V. parvifolium, V. scoparium, V. uliginosum	V. corymbosum, V. deliciosum, V. macrocarpon, V. membranaceum, V. myrtillus, V. ovalifolium, V. ovatum, V. oxycoccos, V. parvifolium, V. scoparium, V. uliginosum
Synonyms		Vaccinium caespitosum var. caespitosum
Web links	Local floras: BC, OR, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Vaccinium caespitosum

whortleberry

dwarf bilberry

Habit

Shrubs deciduous, up to 4 dm; branching habit open, rarely weakly “broom-like”; twigs strongly angled, green to greenish brown, sparsely puberulent along grooves, sometimes glabrous; rhizomatous.

Shrubs deciduous, up to 6 dm; twigs yellow-green to reddish, round in cross section to angled, glabrous to puberulent; rhizomatous.

Leaves

elliptic to ovate, 11–20(30) × 5–10 mm, light green abaxially, green adaxially; thin; flexible;

margins sharply serrate from tips to near base, prominently veined;

tips acute;

surfaces abaxially glandular, adaxially glabrous.

obovate to oblanceolate, 10–30 × 3–12 mm; thin; flexible, green abaxially;

margins serrate on distal 25–50%, prominently reticulate-veined;

tips rounded, sometimes subacute;

surfaces abaxially glabrous or glandular, adaxially glabrous.

Inflorescences

solitary flowers in axils.

Flowers

sepals 5;

calyces shallowly lobed, glabrous;

petals 5;

corollas ovoid-urceolate to globose, 3–7 × 4–7 mm, white to pink, glaucous;

filaments glabrous.

sepals 5, light green;

calyx lobes vestigial;

petals 5;

corollas cylindric-urceolate to globose, 4–6 × 3–5 mm, white to pink, glaucous;

filaments > anthers, glabrous.

Fruits

4–9 mm in diameter, dark red to bluish black; without a bloom.

5–8 mm in diameter, blue to bluish black, with a bloom.

=24, 48.

=24.

Vaccinium caespitosum

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Wet mid- to high elevation areas. Flowering Apr–Jul. 1100–2100 m. BW, Casc, Sisk. ID, NV, WA; northeast to Alberta and southeast to NM, Greenland; Asia, Europe. Native.

Morphologically, Vaccinium myrtillus is similar to V. scoparium, and at higher elevations their ranges overlap. Vaccinium myrtillus differs from V. scoparium by its generally larger leaves and flowers, often sparsely puberulent twigs, and its broom-like habit.

Wet meadows to rocky mountain slopes. Flowering Apr–Aug. 50–2800 m. BR, BW, Casc, CR, ECas, Est, WV. CA, ID, WA; north to AK, east to Newfoundland, south to Guatemala. Native.

Morphologically, V. caespitosum is very similar to V. deliciosum, making identification of these species difficult, particularly at higher elevations where their ranges overlap. The chromosome numbers of V. caespitosum (2n=24) and V. deliciosum (2n=48) may indicate that V. deliciosum is an autopolyploid derivative of V. caespitosum.