BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Vaccinium angustifolium | Low Sweet Blueberry 



GENERAL BOTANICAL CHARACTERISTICS : 
Low sweet blueberry is an erect, low-growing, variable shrub that
reaches 2 to 24 inches (5-60 cm) in height [17,34,141,157].  It
typically forms dense, extensive colonies [157].  Roots are shallow and
fibrous but may possess a taproot, which can extend to 3 feet (1 m) in
depth [17,66,72].  Woody rhizomes average 0.18 inch (4.5 mm) in diameter
and 2.4 inches (6 cm) in depth [56].

Flowers are borne in short, few-flowered terminals or axillary racemes
[94,111,157].  Fruit is a globular berry averaging 0.12 to 0.4 inch
(4-11 mm) in diameter [94,150]; some cultivars produce fruit up to 1
inch (2.5 cm) in diameter [7].  The berries are very sweet [150].  Each
contains numerous nutlets averaging approximately 0.04 inch (1.2 mm) in
length [157].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Low sweet blueberry reproduces vegetatively and by seed [72,111].

Seed:  Plants generally first flower at approximately 4 years of age
[72].  Researchers have reported a range of 56 to 64 seeds per berry
[21,153].  Viability ranges from 30 to 50 percent [153].  Some clones
are self-fertile, others self-sterile [1].  Flowers are generally
pollinated by wild bees [119].  Shrubs with relatively few flowers may
fail to attract pollinators, and shrubs with fewer than 30 flowers
rarely produce fruit.  Productive plants may bear more than 400 flowers
[156].

Seed dispersal:  Seeds of low sweet blueberry are dispersed by various
birds and mammals [72,124].  In New England and the Maritime Provinces,
the American robin and black bear are particularly effective long
distance dispersal agents [72,100,,126,154].  Deer mice, chipmunks, and
the red-back vole are important local dispersers [9,100].

Seedbanking:  Seedbanking has not been documented, but researchers
have reported the presence of seeds within the top layers of soil [65].
Seed can remain viable for up to 12 years when properly stored [124],
and limited seedbanking may occur.

Germination:  In laboratory tests, germination ranged from 30 to 80
percent [153].  Seed germinates best when exposed to light [72].  Fresh
seed germinates readily at 70 degrees Fahrenheit (21 deg C) under a
regime of 16 hours light per 24-hour period [72].  Germination generally
begins within 3 to 4 weeks and continues for 6 to 8 weeks [48].
Stratification and pretreatment with gibberellin can speed germination
[48,125].

Seedling establishment:  Seedling establishment appears variable.
Seedlings are commonly observed in parts of the Maritime Provinces and
in northern Maine [157], where seeds germinate on open sites with high
moisture availability [119].  Seedlings are sometimes observed in
clearcuts, on burned sites, and in abandoned fields [119].  However,
seedlings are rare in eastern Ontario and in many other parts of this
species' range [153].  In Ontario, seedling establishment is unlikely
unless the following conditions occur: (1) a cool spring follows
dispersal, (2) August and September are wet, (3) the winter is mild or
there is a good snow cover, and (4) the spring is wet.  These conditions
have been observed only once during a 40-year period [153].  Poor
seedling establishment is generally attributable to unfavorable soil
temperatures and water stress [142].

Vegetative regeneration:  In many areas, vegetative expansion is the
primary mode of regeneration [8,153].  In the absence of disturbance,
clones increase by expansion of rhizomes [15,119,124].  After fire or
other types of disturbance, plants often sprout from the stem base, from
underground rhizomes [157], or from unburned belowground portions of
aerial stems [15].  Rhizomes subjected to heat treatment often develop
significantly greater numbers of shoots than do untreated rhizomes [56].


SITE CHARACTERISTICS : 
Low sweet blueberry grows in a wide variety of habitats [105].  It
occurs in mixed conifer and hardwood forests, in headlands, high moors,
upland bogs, peaty barrens, along sandy riverbanks, and on exposed rocky
outcrops of the Canadian Shield [49,56,105,157].  Low sweet blueberry is
a prominent component of jack pine (Pinus banksiana) barrens, maple
groves, oak savannas, and poplar regeneration forests [105,145,157].  It
is common in abandoned pastures and clearcuts, and along roadsides
[141,157].

Climate:  Low sweet blueberry is tolerant of a wide range of
temperatures [154].  It grows in areas having a dry, sunny, continental
climatic regime receiving an average of 20 inches (500 mm) of
precipitation annually, as well as in areas having cloudy maritime
climates receiving 61 to 79 inches (1,560-1,950 mm) of precipitation
annually [83].

Shade:  Shade is detrimental to the growth of low sweet blueberry in the
Atlantic Provinces but is necessary for optimal growth in Manitoba's
dry, sunny continental climate [83].

Soils:  Low sweet blueberry is most commonly associated with light,
well-drained acidic soils [124].  Soils generally have a high organic
content but may be relatively low in available mineral nutrients
[29,77].  Soils are often shallow and discontinuous [152].  Low sweet
blueberry grows on loam, sandy loam, gravelly loam, and silt or clay
loam developed from sandstone, shale, or glacial drift [49,78,124].
Parent materials vary but include granite, quartzite, gneiss, shale, and
sandstone pavement [152].  In much of eastern Ontario, soils have formed
over Precambrian bedrock [137].  Low sweet blueberry grows on acidic
soils with pH ranging from 2.8 to 6.6 [157] but reportedly thrives on
soils with a pH of 4.2 to 5.2 [70,97,157].  Plants generally grow better
on undisturbed rather then tilled soil [96].  Low sweet blueberry occurs
at elevations from sea level to 4,950 feet (1,500 m) [72,150].



SUCCESSIONAL STATUS : 
Facultative Seral Species

Low sweet blueberry is an important recolonizer [57].  Its sprouts are
prominent on disturbed sites such as clearcuts, burns, fields, and
pastures [17,72,157].  Cover is typically higher on fields derived from
hayfields than those derived from woodlots [68].  Low sweet blueberry is
an important seral species during the transition from field to forest in
various eastern oldfield communities [72].


SEASONAL DEVELOPMENT : 
Phenological development of low sweet blueberry varies according to
geographic location and specific weather conditions [22,62].
Temperature and day length are important regulatory influences [72,76].
Initial floral development begins in the year prior to flowering and
fruiting [3].  Floral bud primordia appear during June and early July
[22] when day length reaches approximately 15 hours [3].  Development
may continue until late October if air temperatures remain above 32
degrees Fahrenheit (0 deg C) with long periods above 50 degrees
Fahrenheit (10 deg C) [72].  Leaves harden by mid-July, color by late
August, and abciss by late October [72,119].

Plants are dormant in fall [157] and overwinter in a leafless state
[72].  Active annual growth can begin as early as March or April [22],
but in many areas, both vegetative and flower bud development begins in
early May after air temperatures have exceeded 50 degrees Fahremheit (10
deg C) for a least 3 to 4 consecutive days [72].  Vegetative shoots
grow until midsummer [83]. 

Plants generally flower in May or June of their 2nd year [72,167].  A
few flowers may open as early as March in unusually good years, and some
plants occasionally flower as late as September or October [154].
Flowering may be delayed by 2 or 3 weeks in cool, coastal areas [72].
Fruit generally ripens from midsummer to late summer, approximately 50
days after anthesis [171].  In an Ontario study, seed dispersal began
from June 11 to June 20, peaked in early July, and ended in September
[153].  Generalized flowering and fruiting dates for various locations
are as follows:

Location        Flowering               Fruiting         

VA              May-June                July-August [150]
NS              June-late July          early-mid-August [72,157]
Pictou Co.,NS   ----                    July 17- Oct. 27 [151]
ME              ----                    mid July-August [77]
MI              May-June                July-August [44]
NJ              April                   ---- [154]
ON              May-early June          June-September [153,154,141].
         

Related categories for Species: Vaccinium angustifolium | Low Sweet Blueberry