Vaccinium myrtilloides Michx. - Sourtop
By Steven Clemants
Not peer reviewed
Last Modified 02/24/2012
Field IdentificationA low shrub to 3 ft tall with elliptic leaves that are hairy below and with an urceolate flower.
Other uses(Sheppard, 1991)
An important species for assessment of pollution impacts in boreal areas.
This species has been reported from unspecified localities in Orange Co., NY, but no specimens have been seen.
Nomenclature*Vaccinium myrtilloides Michx., Fl. Bor.-Amer. 1: 234. 1803. *Vaccinium pensylvanicum var. myrtilloides (Michx.) Fernald, Rhodora 10: 148. 1908. *Vaccinium angustifolium var. myrtilloides (Michx.) House, New York State Mus. Bull. 243-244: 61. 1923. TYPE: Canada. Quebec: Lake Mistassini, Michaux s.n. (Holotype: P), see (Camp, 1945), (Vander Kloet, 1989).
*Vaccinium canadense Richardson in Franklin, Narr. Journey Polar Sea 736. 1823. TYPE: Location unknown, J. Richardson s.n. (Holotype: BM [Banks herb.]).
*Vaccinium angustifolium var. integrifolium Lepage, Nat. Canada 78: 341. 1951. TYPE: Canada. Quebec: Nouveau-Quebec; Betw. Fort George and la baie aux Oies, 7 Aug 1950, Lepage 12635 (Holotype: DAO).
DescriptionHABIT perennial, deciduous, chamaephyte, shrubs, autotrophic, monoclinous, with adventitious roots or with fibrous roots, 0.2-0.5 m tall, with rhizomes.
STEMS erect, round, not winged, "regular". Prickles absent. Bark furrowed (and warty), not exfoliating, reddish orange or dark violet-red or dark reddish orange. Branches ascending (spreading), dark orange, round, not winged, 1.1-3.2 mm in diam. Twigs orange, not odoriferous, round, 0.4-0.7 mm in diam., warty, hairs short and unbranched, erect, unicellular, uniseriate, white, moderately dense to dense, throughout, not glabrescent, without glands. Pith present, dark yellowish orange, round, continuous, nodal diaphragm absent. Thorns absent. Aerial roots absent. Sap translucent. Resin absent.
BUDS terminal and axillary buds monomorphic. Terminal bud present, narrowly ovate, 1.6-2.5 mm long. Axillary buds present, 1, narrowly ovate, 1.5-2.1 mm long, pointed. Bud scales 4, reddish orange or dark orange-red or dark gray, imbricate, narrowly ovate, coriaceous, aristate, glabrous, without glands. Leaf scars crescent, 0.2 mm high, 0.7-0.8 mm wide, with short white hairs around edge. Vascular bundle scars 1, circular, 0.1 mm tall.
LEAVES alternate, 1 per node, spaced ± evenly along stem, divergent from stem, simple. Stipules absent. Leaves sessile. Leaf: abaxial surface greenish yellow or yellowish green, adaxial surface greenish yellow or yellowish green, blades narrowly elliptic or elliptic, plane, symmetric, 1.1-2.5 cm long, 0.7-1 cm wide, chartaceous, base acute, margin ciliate, apex acute and mucronate, abaxial surface hairs long and unbranched, erect, unicellular, uniseriate, white, moderately dense, throughout, not glabrescent, without glands, adaxial surface hairs long and unbranched, appressed or spreading, unicellular, uniseriate, white, sparse, throughout or along midveins, not glabrescent, without glands. Brochidodromous venation, veins 4-5. Leaf lobes absent. Spines absent. Tendrils absent.
INFLORESCENCES monomorphic, regular or, if dimorphic, female inflorescence simple, raceme, terminal or axillary. Peduncle absent. Rachis present, 0.3-0.6 cm long, with bracts. Bracts sessile, blades: abaxial surface reddish orange or orange, adaxial surface reddish orange or orange, narrowly obtrullate or obtrullate, involute, 2.4-2.5 mm long, 0.7-1.4 mm wide, base attenuate, margin entire, apex acuminate, abaxial surface glabrous, without glands, adaxial surface glabrous, without glands. Pedicel 1-1.5 mm long, glabrous or hairs short and unbranched, hairs erect, unicellular, uniseriate, white, dense, throughout, not glabrescent, without glands. Bracteoles 2, sessile, at base of pedicel, not connate, bracteoles: abaxial surface reddish orange or orange, bracteole: adaxial surface reddish orange or orange, elliptic or widely elliptic, involute, 1.5-1.7 mm long, 1-1.1 mm wide, base attenuate, margin entire, apex acute. Cupules absent.
FLOWERS serotinous, formed on short shoots, monomorphic, with sepals and petals readily distinguishable from one another, bisexual. Perfect or female flowers white or light greenish yellow, 5-merous, 4.3-6 mm long, 3.5-4.5 mm wide, 3-6 flowers per inflorescence, perianth of two whorls. Calyx present, actinomorphic, campanulate, of fused sepals, persistent, abaxial and adaxial surfaces the same color, yellowish green, 2.7-2.9 mm long, 3-4 mm wide, tube 1.3-1.4 mm long, calyx limb 0.9-1.4 mm long, 3-4 mm wide. Sepals or sepal lobes 5, widely depressed ovate or depressed ovate, 0.9-1.4 mm long, 1.1-1.5 mm wide, base truncate, margin entire or denticulate, apex acute or acuminate, abaxial surface glabrous, without glands, adaxial surface glabrous, without glands. Epicalyx absent. Corolla present, actinomorphic, urceolate or tubular, of fused petals, deciduous, abaxial and adaxial surfaces the same color, white or light greenish yellow, 4.3-4.9 mm long, 2.6-4.8 mm wide, corolla limb 0.8-1.3 mm long, 2.6-4.8 mm wide. Shallowly deltate or shallowly triangular, 0.8-1.3 mm long, 1.1-1.8 mm wide, base truncate, margin ciliate (papilose), apex acute, abaxial surface papillose, unicellular, uniseriate, white, sparse, apically, not glabrescent, without glands, adaxial surface glabrous, without glands. Gynoecium syncarpous. Carpels 5. Stigmas 1, capitate. Styles not persistent, 1, 3.9-4.4 mm long. Ovary inferior, 1-1.2 mm long, 1.3-1.7 mm wide, nectiferous disk present. Locules 5. Placentation axile. Androecium obdiplostemonous. Stamens 10, 3.5-4.2 mm long. Anthers linear, opening by pores, opening 1/4 of entire anther, bithecal, orange, glabrous. Filaments free, straight, white or violet-red, hairs short and unbranched, appressed, unicellular, uniseriate. Staminodes absent.
FRUITS bacca (berry), blue, globose, 7-9 mm long, 7-9 mm wide, glabrous, without glands.
SEEDS 5 to many, yellowish orange, oblong, 0.9-1.5 mm long, 0.7-1 mm wide, wingless, not tailed, reticulate-foveate.
DistributionMore common in upstate New York, this species has been reported from unspecified localities in Orange Co., NY, but no specimens have been seen.
Rarity StatusHeritage global rank -- ?
Connecticut -- Not listed
New Jersey -- Not listed
New York -- Not listed
May [week 2].
(Bruederle et al., 1991) (Finnamore & Neary, 1978) (Reader, 1977) (Stephen, 1954) (Vander Kloet & Hall, 1981)
Autogamy -- Autogamy is possible but usually not very effective. The species is an obligate outcrosser.
Melittophily -- Flowers are visited primarily by: Andrena carlini Ckll., A. carolina Vier., A. vicina Sm., Bombus perplexus Cr., B. tericola Kby., B. ternarius Say, Lasioglossum quebecense (Cr.), and L. viridatus (Ckll.).
July [week 2].
(Vander Kloet & AustinSmith, 1986) (Vander Kloet & Hall, 1981)
Endozoochory -- Black bear and American Robin are the most important dispersers, but raccoon, white-tailed deer, red fox, porcupine, and Spruce Grouse also favor the berries.
(Vander Kloet & Hall, 1981)
Viability reduced after excretion by birds or mammals, 30% viable under a variety of conditions.