BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Vaccinium corymbosum | Highbush Blueberry 



GENERAL BOTANICAL CHARACTERISTICS : 
Highbush blueberry is a crown-forming deciduous shrub with two to five
stems arising from a single bole.  It typically grows from 6.5 to 10
feet (2-3 m) in height.  The fruit is a sweet, juicy, blue-black berry
about 0.3 to 0.4 inch (7 to 10 mm) in diameter, containing several small
seeds (nutlet) about 0.05 inch (1.2 mm) long [24,26].  


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Highbush blueberry primarily reproduces from seed.  Bees are the primary
pollinator.  It typically produces abundant fruit annually.  In Florida,
5-foot-tall (1.5 m) shrubs annually produc an average of 231,000 ovules,
of which about 11 percent (25,410) develop into seeds [26].  Mature,
commercially grown 8- to 10-year-old plants often yield 8 to 10 pints of
fruit per year [18].

Highbush blueberry seeds are dispersed in the droppings of frugivorous
birds and mammals.  Long-distance dispersal is rare because most animals
which consume highbush blueberries are territorial.  Even when fruit
ripening coincides with migration of songbirds, dispersal distances are
short because berry pulp rarely stays in the gut of cropless birds for
more than 20 minutes [26].  In the southern portion of its range,
highbush blueberry fruits are dispersed sporadically from late March
through June.  These seeds have thick seed coats and require cold
stratification before germination can occur [21].  Germination typically
occurs in the winter following spring dispersal.  In contrast, plants of
northern latitudes have thinner seed coats and germinate in the autumn
shortly after dispersal [27,29].

In Florida, highbush blueberry averaged 16 seeds per berry, of which 57
percent germinated when placed in an illuminated misting chamber [26].
Germination percent is reduced at least 15 percent after passing through
the digestive system of a bird or mammal [9].

Vegetative regeneration:  Highbush blueberry rarely produces rhizomes
except in a few isolated populations in the Florida panhandle, on
isolated mountain peaks in North Carolina and Tennessee, and in eastern
Quebec where it introgresses with low sweet blueberry [25].  Layering
has been observed only in populations in Ontario and Quebec [26].  When
"disturbed or burnt" the plant occasionally produces new plants from
root sprouts 3 to 6 feet (1-2 m) away from the parent [26].


SITE CHARACTERISTICS : 
Highbush blueberry is intolerant of shade [18].  Along the Atlantic
Coast and in the Great Lakes region, highbush blueberry is most
frequently found at relatively low elevatons along the edges of swamps
and bogs; along the sandy margins of lakes, ponds, and streams; and
within open areas of moist woods [18,26].  It is less abundant in
flatwoods, gray birch (Betula populifolia) scrubland, pine barrens,
bayheads, upland ericaceous meadows, upland woods, ravines, and mountain
summits.  It rarely occurs in xeric pine-oak woods and cut-over pine
savannas [26].

Highbush blueberry grows best on hummocks or raised bogs which provide
moist, acidic, well-aerated, highly-organic soils optimal for growth
[17,18].  It is typically observed on soil with pH values between 2.7
and 6.6 and where nitrogen and phosphorus are quite low [24].  Plants
can withstand extended periods of flooding [1].


SUCCESSIONAL STATUS : 
Because of its shade-intolerance, highbush blueberry is restricted to
open swamps and bogs, lakeshores and streamsides, open woods, and
high-elevation balds.  Such habitats represent intermediate stages of
succession.  Highbush blueberry can be eliminated from sites as
overstory cover and shading increase.  In shrub bogs in northern
Illinois, highbush blueberry was largely replaced by the shading and
competitive effects of glossy-leaved buckthorn (Rhamnus framgula) [22].

Fire can be an important factor in creating shade-free environments for
highbush blueberry.  A shrub-carr in New York codominated by mountain
holly and highbush blueberry was created by a severe swamp fire in 1892
which consumed over 3 feet (1 m) of peat.  Although this shrub community
represents an intermediate stage of succession between wet meadow and
forested wetland, it is relatively stable.  Size and age structure of
the two dominant shrubs in 1986 showed an inverse j-shaped distribution
indicative of self-maintaining populations; the dense shrub community
is only slowly progressing to black spruce (Picea mariana) and tamarack
(Larix laricina) [11].


SEASONAL DEVELOPMENT : 
In the southern portion of its range, highbush blueberry flowers
sporadically over a 2- to 3-month period.  North of latitude 44 degrees
N., flowering is synchronous and lasts a maximum of 25 days [24].
Flowers open as the leaves unfold or rarely when the leaves are half
developed [21].  Fruiting begins about 62 days after flowering and is
thus asynchronous in the south and synchronous in the north.  Vander
Kloet and Austin-Smith [27] speculate that the fruit ripening patterns
of highbush blueberry may be related to the nutritional needs of avian
seed dispersers.  Mass fruiting in the north occurs in summer when avian
dispersers are numerous.

Beginning of anthesis is as follows [24]:

south Florida - mid-February
Georgia, Alabama, Mississippi, Louisiana, northern Florida - March
Piedmont - early April
Appalachians and Ouachitas - late April to early May
Carolinas - late March to early April
Virginia, Delaware, New Jersey - late April to early May
Pennsylvania, West Virginia, New York, New England - early to late May
southern Ontario, Michigan - mid-May to early June
eastern Ontario, Quebec - early June to late June
sosuthwestern Nova Scotia - mid-June

Fruit ripening is as follows [24]:

Florida - early April until November
Georgia, North Carolina, South Carolina - May to June, but not until
 August in the mountains
Michigan to Quebec, New York and New England - July and August

Related categories for Species: Vaccinium corymbosum | Highbush Blueberry